Staggered accept request and feedback in sidelink network coding

ABSTRACT

Aspects relate to techniques for delaying accept request messages for sidelink network coded communication. A network coding device can receive from a transmitting wireless communication device a sidelink transmission including a packet and a network coding request flag requesting the network coding device perform retransmission(s) of the packet. The network coding device can then receive feedback information for the first packet from a receiving wireless communication device that received the packet at a first time. In addition, the network coding device can transmit an accept request message to the transmitting device indicating whether the network coding device accepts performing retransmission(s) of the packet at a second time different than the first time.

TECHNICAL FIELD

The technology discussed below relates generally to wirelesscommunication networks, and more particularly, to network coding insidelink

BACKGROUND

Wireless communication between devices may be facilitated by variousnetwork configurations. In one configuration, a cellular network mayenable user equipment (UEs) to communicate with one another throughsignaling with a nearby base station or cell. Another wirelesscommunication network configuration is a device to device (D2D) networkin which UEs may signal one another directly, rather than via anintermediary base station or cell. For example, D2D communicationnetworks may utilize sidelink signaling to facilitate the directcommunication between UEs over a proximity service (ProSe) PC5interface. In some sidelink network configurations, UEs may furthercommunicate in a cellular network, generally under the control of a basestation. Thus, the UEs may be configured for uplink and downlinksignaling via a base station and further for sidelink signaling directlybetween the UEs without transmissions passing through the base station.

Sidelink communication may be transmitted in units of slots in the timedomain and in units of sub-channels in the frequency domain Each slotmay include both sidelink control information (SCI) and sidelink datatraffic. The SCI may be transmitted over a physical sidelink controlchannel (PSCCH), while the sidelink data traffic may be transmitted overa physical sidelink shared channel (PSSCH) within resources reserved ona sidelink carrier by the SCI. A receiving UE may transmit feedbackinformation, such as hybrid automatic repeat request (HARQ) feedbackinformation including an acknowledgement (ACK) or negativeacknowledgement (NACK) of the sidelink data traffic, on a physicalsidelink feedback channel (PSFCH). In some examples, there is a mappingbetween the PSSCH and the corresponding PSFCH resource utilized totransmit the PSFCH.

BRIEF SUMMARY OF SOME EXAMPLES

The following presents a summary of one or more aspects of the presentdisclosure, in order to provide a basic understanding of such aspects.This summary is not an extensive overview of all contemplated featuresof the disclosure and is intended neither to identify key or criticalelements of all aspects of the disclosure nor to delineate the scope ofany or all aspects of the disclosure. Its sole purpose is to presentsome concepts of one or more aspects of the disclosure in a form as aprelude to the more detailed description that is presented later.

In one example, a network coding device is provided. The network codingdevice includes a transceiver, a memory, and a processor coupled to thetransceiver and the memory. The processor and the memory are configuredto receive a first sidelink transmission transmitted from a transmittingwireless communication device to a receiving wireless communicationdevice via the transceiver. The first sidelink transmission includes afirst packet and a first network coding request flag requesting thenetwork coding device perform one or more retransmissions of the firstpacket. The processor and the memory are further configured to receivefeedback information for the first packet from the receiving wirelesscommunication device at a first time via the transceiver, and transmit afirst accept request message to the transmitting wireless communicationdevice at a second time different than the first time via thetransceiver. the first accept request message indicates whether thenetwork coding device accepts performing the one or more retransmissionsof the first packet.

Another example provides a method for wireless communication at anetwork coding device. The method includes receiving a first sidelinktransmission transmitted from a transmitting wireless communicationdevice to a receiving wireless communication device. The first sidelinktransmission includes a first packet and a first network coding requestflag requesting retransmission of the first packet by the network codingdevice. The method further includes receiving feedback information forthe first packet from the receiving wireless communication device at afirst time, and transmitting a first accept request message to thetransmitting wireless communication device at a second time differentthan the first time, the first accept request message indicating whetherthe network coding device accepts the retransmission of the firstpacket.

Another example provides a network coding device including means forreceiving a first sidelink transmission transmitted from a transmittingwireless communication device to a receiving wireless communicationdevice. The first sidelink transmission includes a first packet and afirst network coding request flag requesting retransmission of the firstpacket by the network coding device. The network coding device furtherincludes means for receiving feedback information for the first packetfrom the receiving wireless communication device at a first time, andmeans for transmitting a first accept request message to thetransmitting wireless communication device at a second time differentthan the first time, the first accept request message indicating whetherthe network coding device accepts the retransmission of the firstpacket.

Another example provides a non-transitory computer-readable mediumhaving stored therein instructions executable by one or more processorsof a network coding device to receive a first sidelink transmissiontransmitted from a transmitting wireless communication device to areceiving wireless communication device. The first sidelink transmissionincludes a first packet and a first network coding request flagrequesting retransmission of the first packet by the network codingdevice. The non-transitory computer-readable medium further includesinstructions executable by the one or more processors of the networkcoding device to receive feedback information for the first packet fromthe receiving wireless communication device at a first time, andtransmit a first accept request message to the transmitting wirelesscommunication device at a second time different than the first time, thefirst accept request message indicating whether the network codingdevice accepts the retransmission of the first packet.

Another example provides a transmitting wireless communication deviceincluding a transceiver, a memory, and a processor coupled to thetransceiver and the memory. The processor and the memory are configuredto transmit a sidelink transmission to a receiving wirelesscommunication device and a network coding device via the transceiver.The sidelink transmission including a first packet and a network codingrequest flag requesting the network coding device perform one or moreretransmissions of the first packet. The processor and the memory arefurther configured to receive feedback information for the first packetfrom the receiving wireless communication device at a first time via thetransceiver, and receive an accept request message from the networkcoding device at a second time different than the first time via thetransceiver. The accept request message indicates whether the networkcoding device accepts performing the one or more retransmissions of thefirst packet.

Another example provides a method for wireless communication at atransmitting wireless communication device. The method includestransmitting a sidelink transmission to a receiving wirelesscommunication device and a network coding device. The sidelinktransmission includes a first packet and a network coding request flagrequesting retransmission of the first packet by the network codingdevice. The method further includes receiving feedback information forthe first packet from the receiving wireless communication device at afirst time, and receiving an accept request message from the networkcoding device at a second time different than the first time. The acceptrequest message indicates whether the network coding device accepts theretransmission of the first packet.

Another example provides a transmitting wireless communication deviceincluding means for transmitting a sidelink transmission to a receivingwireless communication device and a network coding device. The sidelinktransmission includes a first packet and a network coding request flagrequesting retransmission of the first packet by the network codingdevice. The transmitting wireless communication device further includesmeans for receiving feedback information for the first packet from thereceiving wireless communication device at a first time, and means forreceiving an accept request message from the network coding device at asecond time different than the first time. The accept request messageindicates whether the network coding device accepts the retransmissionof the first packet.

Another example provides a non-transitory computer-readable mediumhaving stored therein instructions executable by one or more processorsof a transmitting wireless communication device to transmit a sidelinktransmission to a receiving wireless communication device and a networkcoding device. The sidelink transmission includes a first packet and anetwork coding request flag requesting retransmission of the firstpacket by the network coding device. The non-transitorycomputer-readable medium further includes instructions executable by theone or more processors of the transmitting wireless communication deviceto receive feedback information for the first packet from the receivingwireless communication device at a first time, and receive an acceptrequest message from the network coding device at a second timedifferent than the first time. The accept request message indicateswhether the network coding device accepts the retransmission of thefirst packet.

These and other aspects will become more fully understood upon a reviewof the detailed description, which follows. Other aspects, features, andexamples will become apparent to those of ordinary skill in the art,upon reviewing the following description of specific, exemplary examplesof in conjunction with the accompanying figures. While features may bediscussed relative to certain examples and figures below, all examplescan include one or more of the advantageous features discussed herein.In other words, while one or more examples may be discussed as havingcertain advantageous features, one or more of such features may also beused in accordance with the various examples discussed herein. Insimilar fashion, while exemplary examples may be discussed below asdevice, system, or method examples such exemplary examples can beimplemented in various devices, systems, and methods.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating an example of a wireless radio accessnetwork according to some aspects.

FIG. 2 is a diagram illustrating an example of a frame structure for usein a wireless communication network according to some aspects.

FIG. 3 is a diagram illustrating an example of a wireless communicationnetwork employing sidelink communication according to some aspects.

FIGS. 4A and 4B are diagrams illustrating examples of sidelink slotstructures according to some aspects.

FIG. 5 is a diagram illustrating an example of a sidelink slot structurewith feedback resources according to some aspects.

FIG. 6 is a diagram illustrating an example of initial sidelinktranmissions for network coding according to some aspects.

FIG. 7 is a diagram illustrating an example of a network codedretransmission according to some aspects.

FIGS. 8A and 8B are diagrams illustrating exemplary feedback for initialsidelink transmissions and network coded sidelink transmissionsaccording to some aspects.

FIG. 9 is a diagram illustrating exemplary signaling for sidelinknetwork coding according to some aspects.

FIG. 10 is a diagram illustrating exemplary signaling for delayingaccept request messages in sidelink network coding according to someaspects.

FIG. 11 is a flow chart illustrating an exemplary process for slot-baseddelay of accept request messages in sidelink network coding according tosome aspects.

FIG. 12 is a flow chart illustrating an exemplary process fortimer-based staggering of accept request messages and feedbackinformation in sidelink network coding according to some aspects.

FIG. 13 is a flow chart illustrating an exemplary process fortimer-based staggering of accept request messages and feedbackinformation according to some aspects.

FIG. 14 is a diagram illustrating exemplary signaling for includingaccept request messages within network coded retransmissions accordingto some aspects.

FIG. 15 is a diagram illustrating an exemplary network coded sidelinktransmission including an accept request message according to someaspects.

FIG. 16 is a block diagram illustrating an example of a hardwareimplementation for a wireless communication device employing aprocessing system according to some aspects.

FIG. 17 is a flow chart of an exemplary method for receiving delayedaccept request messages in network coding according to some aspects.

FIG. 18 is a block diagram illustrating an example of a hardwareimplementation for a network coding device employing a processing systemaccording to some aspects.

FIG. 19 is a flow chart of an exemplary method for delaying acceptrequest messages in network coding according to some aspects.

DETAILED DESCRIPTION

The detailed description set forth below in connection with the appendeddrawings is intended as a description of various configurations and isnot intended to represent the only configurations in which the conceptsdescribed herein may be practiced. The detailed description includesspecific details for the purpose of providing a thorough understandingof various concepts. However, it will be apparent to those skilled inthe art that these concepts may be practiced without these specificdetails. In some instances, well known structures and components areshown in block diagram form in order to avoid obscuring such concepts.

Network coding may be utilized, for example, for sidelink retransmissionof one or more packets by a network coding device. For example, atransmitting wireless communication device (e.g., a UE) may transmit aninitial sidelink transmission of a packet to one or more receivingwireless communication devices (e.g., UEs) and a network coding deviceover a sidelink data channel (e.g., a PSSCH). The initial sidelinktransmission may include a network coding request flag that requests thenetwork coding device to perform one or more sidelink retransmissions ofthe packet. The network coding device may then transmit an acceptrequest message to the transmitting UE indicating whether the networkcoding device accepts the retransmission(s) of the packet. Uponacceptance of the retransmission(s), the network coding device may thenretransmit the packet to the one or more receiving UEs as a networkcoded sidelink transmission. The network coded sidelink transmission mayinclude, for example, a function of the packet and one or more otherpackets, to be retransmitted to the receiving UEs. The network codingdevice may be, for example, a roadside unit (RSU), another UE (includingone of the receiving UEs), or a base station.

In some examples, turning over retransmissions of the packet to thenetwork coding device may increase the reliability of the packet. Forexample, the network coding device may be configured to perform moreretransmissions than the original transmitting UE. In some examples, thenetwork coding device may select packets for inclusion in a networkcoded sidelink transmission based on feedback information (e.g., HARQACK/NACK) from each of the receiving UEs based on the initial sidelinktransmission of the packet from the transmitting UE. In examples inwhich the network coding device transmits the accept request message atthe same time (e.g., within the same slot) as the feedback information,the network coding device may not receive the feedback information dueto a half-duplex constraint.

Various aspects of the disclosure relate to techniques for delayingaccept request messages for sidelink network coded communication. Bydelaying the accept request message, the network coding device mayreceive the feedback information and use the feedback information forselection of packets to include in the network coded transmission.

In some examples, the network coding device may delay the accept requestmessage by a number of slots from the feedback information. For example,the number of slots may correspond to a difference between a first timeat which the feedback information is sent and a second time at which theaccept request message is sent. In some examples, the network codingdevice may delay transmission of the accept request message based on atimer. For example, the network coding device may initialize (set) atimer upon receipt of the initial sidelink transmission including thepacket and network coding request flag and transmit the accept requestmessage upon expiration of the timer. In some examples, the networkcoding device may delay transmission of the accept request message byincluding the accept request message in the network coded sidelinktransmission or another network coded packet.

While aspects and examples are described in this application byillustration to some examples, those skilled in the art will understandthat additional implementations and use cases may come about in manydifferent arrangements and scenarios. Innovations described herein maybe implemented across many differing platform types, devices, systems,shapes, sizes, and packaging arrangements. For example, aspects and/oruses may come about via integrated chip examples and othernon-module-component based devices (e.g., end-user devices, vehicles,communication devices, computing devices, industrial equipment,retail/purchasing devices, medical devices, AI-enabled devices, etc.).While some examples may or may not be specifically directed to use casesor applications, a wide assortment of applicability of describedinnovations may occur. Implementations may range a spectrum fromchip-level or modular components to non-modular, non-chip-levelimplementations and further to aggregate, distributed, or OEM devices orsystems incorporating one or more aspects of the described innovations.In some practical settings, devices incorporating described aspects andfeatures may also necessarily include additional components and featuresfor implementation and practice of claimed and described examples. Forexample, transmission and reception of wireless signals necessarilyincludes a number of components for analog and digital purposes (e.g.,hardware components including antenna, RF-chains, power amplifiers,modulators, buffer, processor(s), interleaver, adders/summers, etc.). Itis intended that innovations described herein may be practiced in a widevariety of devices, chip-level components, systems, distributedarrangements, disaggregated arrangements (e.g., base station or UE)end-user devices, etc. of varying sizes, shapes, and constitution.

The various concepts presented throughout this disclosure may beimplemented across a broad variety of telecommunication systems, networkarchitectures, and communication standards. Referring now to FIG. 1 , asan illustrative example without limitation, a schematic illustration ofa radio access network 100 is provided. The RAN 100 may implement anysuitable wireless communication technology or technologies to provideradio access. As one example, the RAN 100 may operate according to3^(rd) Generation Partnership Project (3GPP) New Radio (NR)specifications, often referred to as 5G. As another example, the RAN 100may operate under a hybrid of 5G NR and Evolved Universal TerrestrialRadio Access Network (eUTRAN) standards, often referred to as LTE. The3GPP refers to this hybrid RAN as a next-generation RAN, or NG-RAN. Ofcourse, many other examples may be utilized within the scope of thepresent disclosure.

The geographic region covered by the radio access network 100 may bedivided into a number of cellular regions (cells) that can be uniquelyidentified by a user equipment (UE) based on an identificationbroadcasted over a geographical area from one access point or basestation. FIG. 1 illustrates cells 102, 104, 106, and cell 108, each ofwhich may include one or more sectors (not shown). A sector is asub-area of a cell. All sectors within one cell are served by the samebase station. A radio link within a sector can be identified by a singlelogical identification belonging to that sector. In a cell that isdivided into sectors, the multiple sectors within a cell can be formedby groups of antennas with each antenna responsible for communicationwith UEs in a portion of the cell.

In general, a respective base station (BS) serves each cell. Broadly, abase station is a network element in a radio access network responsiblefor radio transmission and reception in one or more cells to or from aUE. A BS may also be referred to by those skilled in the art as a basetransceiver station (BTS), a radio base station, a radio transceiver, atransceiver function, a basic service set (BSS), an extended service set(ESS), an access point (AP), a Node B (NB), an eNode B (eNB), a gNode B(gNB), a transmission and reception point (TRP), or some other suitableterminology. In some examples, a base station may include two or moreTRPs that may be collocated or non-collocated. Each TRP may communicateon the same or different carrier frequency within the same or differentfrequency band. In examples where the RAN 100 operates according to boththe LTE and 5G NR standards, one of the base stations may be an LTE basestation, while another base station may be a 5G NR base station.

Various base station arrangements can be utilized. For example, in FIG.1 , two base stations 110 and 112 are shown in cells 102 and 104; and athird base station 114 is shown controlling a remote radio head (RRH)116 in cell 106. That is, a base station can have an integrated antennaor can be connected to an antenna or RRH by feeder cables. In theillustrated example, the cells 102, 104, and 106 may be referred to asmacrocells, as the base stations 110, 112, and 114 support cells havinga large size. Further, a base station 118 is shown in the cell 108 whichmay overlap with one or more macrocells. In this example, the cell 108may be referred to as a small cell (e.g., a microcell, picocell,femtocell, home base station, home Node B, home eNode B, etc.), as thebase station 118 supports a cell having a relatively small size. Cellsizing can be done according to system design as well as componentconstraints.

It is to be understood that the radio access network 100 may include anynumber of wireless base stations and cells. Further, a relay node may bedeployed to extend the size or coverage area of a given cell. The basestations 110, 112, 114, 118 provide wireless access points to a corenetwork for any number of mobile apparatuses.

FIG. 1 further includes an unmanned aerial vehicle (UAV) 120, which maybe a drone or quadcopter. The UAV 120 may be configured to function as abase station, or more specifically as a mobile base station. That is, insome examples, a cell may not necessarily be stationary, and thegeographic area of the cell may move according to the location of amobile base station such as the UAV 120.

In general, base stations may include a backhaul interface forcommunication with a backhaul portion (not shown) of the network. Thebackhaul may provide a link between a base station and a core network(not shown), and in some examples, the backhaul may provideinterconnection between the respective base stations. The core networkmay be a part of a wireless communication system and may be independentof the radio access technology used in the radio access network. Varioustypes of backhaul interfaces may be employed, such as a direct physicalconnection, a virtual network, or the like using any suitable transportnetwork.

The RAN 100 is illustrated supporting wireless communication formultiple mobile apparatuses. A mobile apparatus is commonly referred toas user equipment (UE) in standards and specifications promulgated bythe 3rd Generation Partnership Project (3GPP), but may also be referredto by those skilled in the art as a mobile station (MS), a subscriberstation, a mobile unit, a subscriber unit, a wireless unit, a remoteunit, a mobile device, a wireless device, a wireless communicationsdevice, a remote device, a mobile subscriber station, an access terminal(AT), a mobile terminal, a wireless terminal, a remote terminal, ahandset, a terminal, a user agent, a mobile client, a client, or someother suitable terminology. A UE may be an apparatus that provides auser with access to network services.

Within the present document, a “mobile” apparatus need not necessarilyhave a capability to move, and may be stationary. The term mobileapparatus or mobile device broadly refers to a diverse array of devicesand technologies. For example, some non-limiting examples of a mobileapparatus include a mobile, a cellular (cell) phone, a smart phone, asession initiation protocol (SIP) phone, a laptop, a personal computer(PC), a notebook, a netbook, a smartbook, a tablet, a personal digitalassistant (PDA), and a broad array of embedded systems, e.g.,corresponding to an “Internet of things” (IoT). A mobile apparatus mayadditionally be an automotive or other transportation vehicle, a remotesensor or actuator, a robot or robotics device, a satellite radio, aglobal positioning system (GPS) device, an object tracking device, adrone, a multi-copter, a quad-copter, a remote control device, aconsumer and/or wearable device, such as eyewear, a wearable camera, avirtual reality device, a smart watch, a health or fitness tracker, adigital audio player (e.g., MP3 player), a camera, a game console, etc.A mobile apparatus may additionally be a digital home or smart homedevice such as a home audio, video, and/or multimedia device, anappliance, a vending machine, intelligent lighting, a home securitysystem, a smart meter, etc. A mobile apparatus may additionally be asmart energy device, a security device, a solar panel or solar array, amunicipal infrastructure device controlling electric power (e.g., asmart grid), lighting, water, etc., an industrial automation andenterprise device, a logistics controller, agricultural equipment, etc.Still further, a mobile apparatus may provide for connected medicine ortelemedicine support, i.e., health care at a distance. Telehealthdevices may include telehealth monitoring devices and telehealthadministration devices, whose communication may be given preferentialtreatment or prioritized access over other types of information, e.g.,in terms of prioritized access for transport of critical service data,and/or relevant QoS for transport of critical service data.

Within the RAN 100, the cells may include UEs that may be incommunication with one or more sectors of each cell. For example, UEs122 and 124 may be in communication with base station 110; UEs 126 and128 may be in communication with base station 112; UEs 130 and 132 maybe in communication with base station 114 by way of RRH 116; UE 134 maybe in communication with base station 118; and UE 136 may be incommunication with mobile base station 120. Here, each base station 110,112, 114, 118, and 120 may be configured to provide an access point to acore network (not shown) for all the UEs in the respective cells. Insome examples, the UAV 120 (e.g., the quadcopter) can be a mobilenetwork node and may be configured to function as a UE. For example, theUAV 120 may operate within cell 102 by communicating with base station110.

Wireless communication between a RAN 100 and a UE (e.g., UE 122 or 124)may be described as utilizing an air interface. Transmissions over theair interface from a base station (e.g., base station 110) to one ormore UEs (e.g., UE 122 and 124) may be referred to as downlink (DL)transmission. In accordance with certain aspects of the presentdisclosure, the term downlink may refer to a point-to-multipointtransmission originating at a scheduling entity (described furtherbelow; e.g., base station 110). Another way to describe this scheme maybe to use the term broadcast channel multiplexing. Transmissions from aUE (e.g., UE 122) to a base station (e.g., base station 110) may bereferred to as uplink (UL) transmissions. In accordance with furtheraspects of the present disclosure, the term uplink may refer to apoint-to-point transmission originating at a scheduled entity (describedfurther below; e.g., UE 122).

For example, DL transmissions may include unicast or broadcasttransmissions of control information and/or traffic information (e.g.,user data traffic) from a base station (e.g., base station 110) to oneor more UEs (e.g., UEs 122 and 124), while UL transmissions may includetransmissions of control information and/or traffic informationoriginating at a UE (e.g., UE 122). In addition, the uplink and/ordownlink control information and/or traffic information may betime-divided into frames, subframes, slots, and/or symbols. As usedherein, a symbol may refer to a unit of time that, in an orthogonalfrequency division multiplexed (OFDM) waveform, carries one resourceelement (RE) per sub-carrier. A slot may carry 7 or 14 OFDM symbols. Asubframe may refer to a duration of 1 ms. Multiple subframes or slotsmay be grouped together to form a single frame or radio frame. Withinthe present disclosure, a frame may refer to a predetermined duration(e.g., 10 ms) for wireless transmissions, with each frame consisting of,for example, 10 subframes of 1 ms each. Of course, these definitions arenot required, and any suitable scheme for organizing waveforms may beutilized, and various time divisions of the waveform may have anysuitable duration.

In some examples, access to the air interface may be scheduled, whereina scheduling entity (e.g., a base station) allocates resources (e.g.,time—frequency resources) for communication among some or all devicesand equipment within its service area or cell. Within the presentdisclosure, as discussed further below, the scheduling entity may beresponsible for scheduling, assigning, reconfiguring, and releasingresources for one or more scheduled entities. That is, for scheduledcommunication, UEs or scheduled entities utilize resources allocated bythe scheduling entity.

Base stations are not the only entities that may function as ascheduling entity. That is, in some examples, a UE may function as ascheduling entity, scheduling resources for one or more scheduledentities (e.g., one or more other UEs). For example, two or more UEs(e.g., UEs 138, 140, and 142) may communicate with each other usingsidelink signals 137 without relaying that communication through a basestation. In some examples, the UEs 138, 140, and 142 may each functionas a scheduling entity or transmitting sidelink device and/or ascheduled entity or a receiving sidelink device to schedule resourcesand communicate sidelink signals 137 therebetween without relying onscheduling or control information from a base station. In otherexamples, two or more UEs (e.g., UEs 126 and 128) within the coveragearea of a base station (e.g., base station 112) may also communicatesidelink signals 127 over a direct link (sidelink) without conveyingthat communication through the base station 112. In this example, thebase station 112 may allocate resources to the UEs 126 and 128 for thesidelink communication. In either case, such sidelink signaling 127 and137 may be implemented in a peer-to-peer (P2P) network, adevice-to-device (D2D) network, a vehicle-to-vehicle (V2V) network, avehicle-to-everything (V2X) network, a mesh network, or other suitabledirect link network.

In some examples, a D2D relay framework may be included within acellular network to facilitate relaying of communication to/from thebase station 112 via D2D links (e.g., sidelinks 127 or 137). Forexample, one or more UEs (e.g., UE 128) within the coverage area of thebase station 112 may operate as relaying UEs to extend the coverage ofthe base station 112, improve the transmission reliability to one ormore UEs (e.g., UE 126), and/or to allow the base station to recoverfrom a failed UE link due to, for example, blockage or fading.

Two primary technologies that may be used by V2X networks includededicated short range communication (DSRC) based on IEEE 802.11pstandards and cellular V2X based on LTE and/or 5G (New Radio) standards.Various aspects of the present disclosure may relate to New Radio (NR)cellular V2X networks, referred to herein as V2X networks, forsimplicity. However, it should be understood that the concepts disclosedherein may not be limited to a particular V2X standard or may bedirected to sidelink networks other than V2X networks.

In order for transmissions over the air interface to obtain a low blockerror rate (BLER) while still achieving very high data rates, channelcoding may be used. That is, wireless communication may generallyutilize a suitable error correcting block code. In a typical block code,an information message or sequence is split up into code blocks (CBs),and an encoder (e.g., a CODEC) at the transmitting device thenmathematically adds redundancy to the information message. Exploitationof this redundancy in the encoded information message can improve thereliability of the message, enabling correction for any bit errors thatmay occur due to the noise.

Data coding may be implemented in multiple manners. In early 5G NRspecifications, user data is coded using quasi-cyclic low-density paritycheck (LDPC) with two different base graphs: one base graph is used forlarge code blocks and/or high code rates, while the other base graph isused otherwise. Control information and the physical broadcast channel(PBCH) are coded using Polar coding, based on nested sequences. Forthese channels, puncturing, shortening, and repetition are used for ratematching.

Aspects of the present disclosure may be implemented utilizing anysuitable channel code. Various implementations of base stations and UEsmay include suitable hardware and capabilities (e.g., an encoder, adecoder, and/or a CODEC) to utilize one or more of these channel codesfor wireless communication.

In the RAN 100, the ability for a UE to communicate while moving,independent of their location, is referred to as mobility. The variousphysical channels between the UE and the RAN are generally set up,maintained, and released under the control of an access and mobilitymanagement function (AMF). In some scenarios, the AMF may include asecurity context management function (SCMF) and a security anchorfunction (SEAF) that performs authentication. The SCMF can manage, inwhole or in part, the security context for both the control plane andthe user plane functionality.

In some examples, a RAN 100 may enable mobility and handovers (i.e., thetransfer of a UE's connection from one radio channel to another). Forexample, during a call with a scheduling entity, or at any other time, aUE may monitor various parameters of the signal from its serving cell aswell as various parameters of neighboring cells. Depending on thequality of these parameters, the UE may maintain communication with oneor more of the neighboring cells. During this time, if the UE moves fromone cell to another, or if signal quality from a neighboring cellexceeds that from the serving cell for a given amount of time, the UEmay undertake a handoff or handover from the serving cell to theneighboring (target) cell. For example, UE 124 may move from thegeographic area corresponding to its serving cell 102 to the geographicarea corresponding to a neighbor cell 106. When the signal strength orquality from the neighbor cell 106 exceeds that of its serving cell 102for a given amount of time, the UE 124 may transmit a reporting messageto its serving base station 110 indicating this condition. In response,the UE 124 may receive a handover command, and the UE may undergo ahandover to the cell 106.

In various implementations, the air interface in the RAN 100 may utilizelicensed spectrum, unlicensed spectrum, or shared spectrum. Licensedspectrum provides for exclusive use of a portion of the spectrum,generally by virtue of a mobile network operator purchasing a licensefrom a government regulatory body. Unlicensed spectrum provides forshared use of a portion of the spectrum without need for agovernment-granted license. While compliance with some technical rulesis generally still required to access unlicensed spectrum, generally,any operator or device may gain access. Shared spectrum may fall betweenlicensed and unlicensed spectrum, wherein technical rules or limitationsmay be required to access the spectrum, but the spectrum may still beshared by multiple operators and/or multiple RATs. For example, theholder of a license for a portion of licensed spectrum may providelicensed shared access (LSA) to share that spectrum with other parties,e.g., with suitable licensee-determined conditions to gain access.

The air interface in the RAN 100 may utilize one or more multiplexingand multiple access algorithms to enable simultaneous communication ofthe various devices. For example, 5G NR specifications provide multipleaccess for UL or reverse link transmissions from UEs 122 and 124 to basestation 110, and for multiplexing DL or forward link transmissions fromthe base station 110 to UEs 122 and 124 utilizing orthogonal frequencydivision multiplexing (OFDM) with a cyclic prefix (CP). In addition, forUL transmissions, 5G NR specifications provide support for discreteFourier transform-spread-OFDM (DFT-s-OFDM) with a CP (also referred toas single-carrier FDMA (SC-FDMA)). However, within the scope of thepresent disclosure, multiplexing and multiple access are not limited tothe above schemes, and may be provided utilizing time division multipleaccess (TDMA), code division multiple access (CDMA), frequency divisionmultiple access (FDMA), sparse code multiple access (SCMA), resourcespread multiple access (RSMA), or other suitable multiple accessschemes. Further, multiplexing DL transmissions from the base station110 to UEs 122 and 124 may be provided utilizing time divisionmultiplexing (TDM), code division multiplexing (CDM), frequency divisionmultiplexing (FDM), orthogonal frequency division multiplexing (OFDM),sparse code multiplexing (SCM), or other suitable multiplexing schemes.

Further, the air interface in the RAN 100 may utilize one or moreduplexing algorithms. Duplex refers to a point-to-point communicationlink where both endpoints can communicate with one another in bothdirections. Full-duplex means both endpoints can simultaneouslycommunicate with one another. Half-duplex means only one endpoint cansend information to the other at a time. Half-duplex emulation isfrequently implemented for wireless links utilizing time division duplex(TDD). In TDD, transmissions in different directions on a given channelare separated from one another using time division multiplexing. Thatis, at some times the channel is dedicated for transmissions in onedirection, while at other times the channel is dedicated fortransmissions in the other direction, where the direction may changevery rapidly, e.g., several times per slot. In a wireless link, afull-duplex channel generally relies on physical isolation of atransmitter and receiver, and suitable interference cancellationtechnologies. Full-duplex emulation is frequently implemented forwireless links by utilizing frequency division duplex (FDD) or spatialdivision duplex (SDD). In FDD, transmissions in different directions mayoperate at different carrier frequencies (e.g., within paired spectrum).In SDD, transmissions in different directions on a given channel areseparated from one another using spatial division multiplexing (SDM). Inother examples, full-duplex communication may be implemented withinunpaired spectrum (e.g., within a single carrier bandwidth), wheretransmissions in different directions occur within different sub-bandsof the carrier bandwidth. This type of full-duplex communication may bereferred to herein as sub-band full duplex (SBFD), also known asflexible duplex.

Various aspects of the present disclosure will be described withreference to an OFDM waveform, schematically illustrated in FIG. 2 . Itshould be understood by those of ordinary skill in the art that thevarious aspects of the present disclosure may be applied to an SC-FDMAwaveform in substantially the same way as described herein below. Thatis, while some examples of the present disclosure may focus on an OFDMlink for clarity, it should be understood that the same principles maybe applied as well to SC-FDMA waveforms.

Referring now to FIG. 2 , an expanded view of an exemplary subframe 202is illustrated, showing an OFDM resource grid. However, as those skilledin the art will readily appreciate, the PHY transmission structure forany particular application may vary from the example described here,depending on any number of factors. Here, time is in the horizontaldirection with units of OFDM symbols; and frequency is in the verticaldirection with units of subcarriers of the carrier.

The resource grid 204 may be used to schematically representtime—frequency resources for a given antenna port. That is, in amultiple-input-multiple-output (MIMO) implementation with multipleantenna ports available, a corresponding multiple number of resourcegrids 204 may be available for communication. The resource grid 204 isdivided into multiple resource elements (REs) 206. An RE, which is 1subcarrier×1 symbol, is the smallest discrete part of the time—frequencygrid, and contains a single complex value representing data from aphysical channel or signal. Depending on the modulation utilized in aparticular implementation, each RE may represent one or more bits ofinformation. In some examples, a block of REs may be referred to as aphysical resource block (PRB) or more simply a resource block (RB) 208,which contains any suitable number of consecutive subcarriers in thefrequency domain. In one example, an RB may include 12 subcarriers, anumber independent of the numerology used. In some examples, dependingon the numerology, an RB may include any suitable number of consecutiveOFDM symbols in the time domain Within the present disclosure, it isassumed that a single RB such as the RB 208 entirely corresponds to asingle direction of communication (either transmission or reception fora given device).

A set of continuous or discontinuous resource blocks may be referred toherein as a Resource Block Group (RBG), sub-band, or bandwidth part(BWP). A set of sub-bands or BWPs may span the entire bandwidth.Scheduling of UEs or sidelink devices (hereinafter collectively referredto as UEs) for downlink, uplink, or sidelink transmissions typicallyinvolves scheduling one or more resource elements 206 within one or moresub-bands or bandwidth parts (BWPs). Thus, a UE generally utilizes onlya subset of the resource grid 204. In some examples, an RB may be thesmallest unit of resources that can be allocated to a UE. Thus, the moreRBs scheduled for a UE, and the higher the modulation scheme chosen forthe air interface, the higher the data rate for the UE. The RBs may bescheduled by a base station (e.g., gNB, eNB, etc.) or may beself-scheduled by a UE/sidelink device implementing D2D sidelinkcommunication.

In this illustration, the RB 208 is shown as occupying less than theentire bandwidth of the subframe 202, with some subcarriers illustratedabove and below the RB 208. In a given implementation, the subframe 202may have a bandwidth corresponding to any number of one or more RBs 208.Further, in this illustration, the RB 208 is shown as occupying lessthan the entire duration of the subframe 202, although this is merelyone possible example.

Each 1 ms subframe 202 may consist of one or multiple adjacent slots. Inthe example shown in FIG. 2 , one subframe 202 includes four slots 210,as an illustrative example. In some examples, a slot may be definedaccording to a specified number of OFDM symbols with a given cyclicprefix (CP) length. For example, a slot may include 7 or 12 OFDM symbolswith a nominal CP. Additional examples may include mini-slots, sometimesreferred to as shortened transmission time intervals (TTIs), having ashorter duration (e.g., one to three OFDM symbols). These mini-slots orshortened transmission time intervals (TTIs) may in some cases betransmitted occupying resources scheduled for ongoing slot transmissionsfor the same or for different UEs. Any number of resource blocks may beutilized within a subframe or slot.

An expanded view of one of the slots 210 illustrates the slot 210including a control region 212 and a data region 214. In general, thecontrol region 212 may carry control channels, and the data region 214may carry data channels. Of course, a slot may contain all DL, all UL,or at least one DL portion and at least one UL portion. The structureillustrated in FIG. 2 is merely exemplary in nature, and different slotstructures may be utilized, and may include one or more of each of thecontrol region(s) and data region(s).

Although not illustrated in FIG. 2 , the various REs 206 within a RB 208may be scheduled to carry one or more physical channels, includingcontrol channels, shared channels, data channels, etc. Other REs 206within the RB 208 may also carry pilots or reference signals. Thesepilots or reference signals may provide for a receiving device toperform channel estimation of the corresponding channel, which mayenable coherent demodulation/detection of the control and/or datachannels within the RB 208.

In some examples, the slot 210 may be utilized for broadcast, multicast,groupcast, or unicast communication. For example, a broadcast,multicast, or groupcast communication may refer to a point-to-multipointtransmission by one device (e.g., a base station, UE, or other similardevice) to other devices. Here, a broadcast communication is deliveredto all devices, whereas a multicast or groupcast communication isdelivered to multiple intended recipient devices. A unicastcommunication may refer to a point-to-point transmission by a one deviceto a single other device.

In an example of cellular communication over a cellular carrier via a Uuinterface, for a DL transmission, the scheduling entity (e.g., a basestation) may allocate one or more REs 206 (e.g., within the controlregion 212) to carry DL control information including one or more DLcontrol channels, such as a physical downlink control channel (PDCCH),to one or more scheduled entities (e.g., UEs). The PDCCH carriesdownlink control information (DCI) including but not limited to powercontrol commands (e.g., one or more open loop power control parametersand/or one or more closed loop power control parameters), schedulinginformation, a grant, and/or an assignment of REs for DL and ULtransmissions. The PDCCH may further carry HARQ feedback transmissionssuch as an acknowledgment (ACK) or negative acknowledgment (NACK). HARQis a technique well-known to those of ordinary skill in the art, whereinthe integrity of packet transmissions may be checked at the receivingside for accuracy, e.g., utilizing any suitable integrity checkingmechanism, such as a checksum or a cyclic redundancy check (CRC). If theintegrity of the transmission is confirmed, an ACK may be transmitted,whereas if not confirmed, a NACK may be transmitted. In response to aNACK, the transmitting device may send a HARQ retransmission, which mayimplement chase combining, incremental redundancy, etc.

The base station may further allocate one or more REs 206 (e.g., in thecontrol region 212 or the data region 214) to carry other DL signals,such as a demodulation reference signal (DMRS); a phase-trackingreference signal (PT-RS); a channel state information (CSI) referencesignal (CSI-RS); and a synchronization signal block (SSB). SSBs may bebroadcast at regular intervals based on a periodicity (e.g., 5, 10, 20,20, 80, or 120 ms). An SSB includes a primary synchronization signal(PSS), a secondary synchronization signal (SSS), and a physicalbroadcast control channel (PBCH). A UE may utilize the PSS and SSS toachieve radio frame, subframe, slot, and symbol synchronization in thetime domain, identify the center of the channel (system) bandwidth inthe frequency domain, and identify the physical cell identity (PCI) ofthe cell.

The PBCH in the SSB may further include a master information block (MIB)that includes various system information, along with parameters fordecoding a system information block (SIB). The SIB may be, for example,a SystemInformationType 1 (SIB1) that may include various additionalsystem information. The MIB and SIB1 together provide the minimum systeminformation (SI) for initial access. Examples of system informationtransmitted in the MIB may include, but are not limited to, a subcarrierspacing (e.g., default downlink numerology), system frame number, aconfiguration of a PDCCH control resource set (CORESET) (e.g., PDCCHCORESET0), a cell barred indicator, a cell reselection indicator, araster offset, and a search space for SIB1. Examples of remainingminimum system information (RMSI) transmitted in the SIB1 may include,but are not limited to, a random access search space, a paging searchspace, downlink configuration information, and uplink configurationinformation.

In an UL transmission, the scheduled entity (e.g., UE) may utilize oneor more REs 206 to carry UL control information (UCI) including one ormore UL control channels, such as a physical uplink control channel(PUCCH), to the scheduling entity. UCI may include a variety of packettypes and categories, including pilots, reference signals, andinformation configured to enable or assist in decoding uplink datatransmissions. Examples of uplink reference signals may include asounding reference signal (SRS) and an uplink DMRS. In some examples,the UCI may include a scheduling request (SR), i.e., request for thescheduling entity to schedule uplink transmissions. Here, in response tothe SR transmitted on the UCI, the scheduling entity may transmitdownlink control information (DCI) that may schedule resources foruplink packet transmissions. UCI may also include HARQ feedback, channelstate feedback (CSF), such as a CSI report, or any other suitable UCI.

In addition to control information, one or more REs 206 (e.g., withinthe data region 214) may be allocated for data traffic. Such datatraffic may be carried on one or more traffic channels, such as, for aDL transmission, a physical downlink shared channel (PDSCH); or for anUL transmission, a physical uplink shared channel (PUSCH). In someexamples, one or more REs 206 within the data region 214 may beconfigured to carry other signals, such as one or more SIBs and DMRSs.

In an example of sidelink communication over a sidelink carrier via aPC5 interface, the control region 212 of the slot 210 may include aphysical sidelink control channel (PSCCH) including sidelink controlinformation (SCI) transmitted by an initiating (transmitting) sidelinkdevice (e.g., Tx V2X device or other Tx UE) towards a set of one or moreother receiving sidelink devices (e.g., Rx V2X device or other Rx UE).The data region 214 of the slot 210 may include a physical sidelinkshared channel (PSSCH) including sidelink data traffic transmitted bythe initiating (transmitting) sidelink device within resources reservedover the sidelink carrier by the transmitting sidelink device via theSCI. Other information may further be transmitted over various REs 206within slot 210. For example, HARQ feedback information may betransmitted in a physical sidelink feedback channel (PSFCH) within theslot 210 from the receiving sidelink device to the transmitting sidelinkdevice. In addition, one or more reference signals, such as a sidelinkSSB, a sidelink CSI-RS, a sidelink SRS, a sidelink DMRS, and/or asidelink positioning reference signal (PRS) may be transmitted withinthe slot 210.

These physical channels described above are generally multiplexed andmapped to transport channels for handling at the medium access control(MAC) layer. Transport channels carry blocks of information calledtransport blocks (TB). The transport block size (TBS), which maycorrespond to a number of bits of information, may be a controlledparameter, based on the modulation and coding scheme (MCS) and thenumber of RBs in a given transmission.

The channels or carriers illustrated in FIG. 2 are not necessarily allof the channels or carriers that may be utilized between devices, andthose of ordinary skill in the art will recognize that other channels orcarriers may be utilized in addition to those illustrated, such as othertraffic, control, and feedback channels.

FIG. 3 illustrates an example of a wireless communication network 300configured to support D2D or sidelink communication. In some examples,sidelink communication may include V2X communication. V2X communicationinvolves the wireless exchange of information directly between not onlyvehicles (e.g., vehicles 302 and 304) themselves, but also directlybetween vehicles 302/304 and infrastructure (e.g., roadside units (RSUs)306), such as streetlights, buildings, traffic cameras, tollbooths orother stationary objects, vehicles 302/304 and pedestrians 308, andvehicles 302/304 and wireless communication networks (e.g., base station310). In some examples, V2X communication may be implemented inaccordance with the New Radio (NR) cellular V2X standard defined by3GPP, Release 16, or other suitable standard.

V2X communication enables vehicles 302 and 304 to obtain informationrelated to the weather, nearby accidents, road conditions, activities ofnearby vehicles and pedestrians, objects nearby the vehicle, and otherpertinent information that may be utilized to improve the vehicledriving experience and increase vehicle safety. For example, such V2Xdata may enable autonomous driving and improve road safety and trafficefficiency. For example, the exchanged V2X data may be utilized by a V2Xconnected vehicle 302 and 304 to provide in-vehicle collision warnings,road hazard warnings, approaching emergency vehicle warnings,pre-/post-crash warnings and information, emergency brake warnings,traffic jam ahead warnings, lane change warnings, intelligent navigationservices, and other similar information. In addition, V2X data receivedby a V2X connected mobile device of a pedestrian/cyclist 308 may beutilized to trigger a warning sound, vibration, flashing light, etc., incase of imminent danger.

The sidelink communication between vehicle-UEs (V-UEs) 302 and 304 orbetween a V-UE 302 or 304 and either an RSU 306 or a pedestrian-UE(P-UE) 308 may occur over a sidelink 312 utilizing a proximity service(ProSe) PC5 interface. In various aspects of the disclosure, the PC5interface may further be utilized to support D2D sidelink 312communication in other proximity use cases (e.g., other than V2X).Examples of other proximity use cases may include smart wearables,public safety, or commercial (e.g., entertainment, education, office,medical, and/or interactive) based proximity services. In the exampleshown in FIG. 3 , ProSe communication may further occur between UEs 314and 316.

ProSe communication may support different operational scenarios, such asin-coverage, out-of-coverage, and partial coverage. Out-of-coveragerefers to a scenario in which UEs (e.g., UEs 314 and 316) are outside ofthe coverage area of a base station (e.g., base station 310), but eachare still configured for ProSe communication. Partial coverage refers toa scenario in which some of the UEs (e.g., V-UE 304) are outside of thecoverage area of the base station 310, while other UEs (e.g., V-UE 302and P-UE 308) are in communication with the base station 310.In-coverage refers to a scenario in which UEs (e.g., V-UE 302 and P-UE308) are in communication with the base station 310 (e.g., gNB) via a Uu(e.g., cellular interface) connection to receive ProSe serviceauthorization and provisioning information to support ProSe operations.

To facilitate D2D sidelink communication between, for example, UEs 314and 316 over the sidelink 312, the UEs 314 and 316 may transmitdiscovery signals therebetween. In some examples, each discovery signalmay include a synchronization signal, such as a primary synchronizationsignal (PSS) and/or a secondary synchronization signal (SSS) thatfacilitates device discovery and enables synchronization ofcommunication on the sidelink 312. For example, the discovery signal maybe utilized by the UE 316 to measure the signal strength and channelstatus of a potential sidelink (e.g., sidelink 312) with another UE(e.g., UE 314). The UE 316 may utilize the measurement results to selecta UE (e.g., UE 314) for sidelink communication or relay communication.

In 5G NR sidelink, sidelink communication may utilize transmission orreception resource pools. For example, the minimum resource allocationunit in frequency may be a sub-channel (e.g., which may include, forexample, 10, 15, 20, 25, 50, 75, or 100 consecutive resource blocks) andthe minimum resource allocation unit in time may be one slot. The numberof sub-channels in a resource pool may include between one andtwenty-seven sub-channels. A radio resource control (RRC) configurationof the resource pools may be either pre-configured (e.g., a factorysetting on the UE determined, for example, by sidelink standards orspecifications) or configured by a base station (e.g., base station310).

In addition, there may be two main resource allocation modes ofoperation for sidelink (e.g., PC5) communications. In a first mode, Mode1, a base station (e.g., gNB) 310 may allocate resources to sidelinkdevices (e.g., V2X devices or other sidelink devices) for sidelinkcommunication between the sidelink devices in various manners. Forexample, the base station 310 may allocate sidelink resourcesdynamically (e.g., a dynamic grant) to sidelink devices, in response torequests for sidelink resources from the sidelink devices. For example,the base station 310 may schedule the sidelink communication via DCI3_0. In some examples, the base station 310 may schedule the PSCCH/PSSCHwithin uplink resources indicated in DCI 3_0. The base station 310 mayfurther activate preconfigured sidelink grants (e.g., configured grants)for sidelink communication among the sidelink devices. In some examples,the base station 310 may activate a configured grant (CG) via RRCsignaling. In Mode 1, sidelink feedback may be reported back to the basestation 310 by a transmitting sidelink device.

In a second mode, Mode 2, the sidelink devices may autonomously selectsidelink resources for sidelink communication therebetween. In someexamples, a transmitting sidelink device may perform resource/channelsensing to select resources (e.g., sub-channels) on the sidelink channelthat are unoccupied. Signaling on the sidelink is the same between thetwo modes. Therefore, from a receiver's point of view, there is nodifference between the modes.

In some examples, sidelink (e.g., PC5) communication may be scheduled byuse of sidelink control information (SCI). SCI may include two SCIstages. Stage 1 sidelink control information (first stage SCI) may bereferred to herein as SCI-1. Stage 2 sidelink control information(second stage SCI) may be referred to herein as SCI-2.

SCI-1 may be transmitted on a physical sidelink control channel (PSCCH).SCI-1 may include information for resource allocation of a sidelinkresource and for decoding of the second stage of sidelink controlinformation (i.e., SCI-2). For example, SCI-1 may include a physicalsidelink shared channel (PSSCH) resource assignment and a resourcereservation period (if enabled). SCI-1 may further identify a prioritylevel (e.g., Quality of Service (QoS)) of a PSSCH. For example,ultra-reliable-low-latency communication (URLLC) traffic may have ahigher priority than text message traffic (e.g., short message service(SMS) traffic). Additionally, SCI-1 may include a PSSCH demodulationreference signal (DMRS) pattern (if more than one pattern isconfigured). The DMRS may be used by a receiver for radio channelestimation for demodulation of the associated physical channel. Asindicated, SCI-1 may also include information about the SCI-2, forexample, SCI-1 may disclose the format of the SCI-2. Here, the formatindicates the resource size of SCI-2 (e.g., a number of REs that areallotted for SCI-2), a number of a PSSCH DMRS port(s), and a modulationand coding scheme (MCS) index. In some examples, SCI-1 may use two bitsto indicate the SCI-2 format. Thus, in this example, four differentSCI-2 formats may be supported. SCI-1 may include other information thatis useful for establishing and decoding a PSSCH resource.

SCI-2 may also be transmitted on the PSCCH and may contain informationfor decoding the PSSCH. According to some aspects, SCI-2 includes a16-bit layer 1 (L1) destination identifier (ID), an 8-bit L1 source ID,a hybrid automatic repeat request (HARQ) process ID, a new dataindicator (NDI), and a redundancy version (RV). For unicastcommunications, SCI-2 may further include a CSI report trigger. Forgroupcast communications, SCI-2 may further include a zone identifierand a maximum communication range for NACK. SCI-2 may include otherinformation that is useful for establishing and decoding a PSSCHresource.

In some examples, the SCI (e.g., SCI-1 and/or SCI-2) may further includea resource assignment of retransmission resources reserved for one ormore retransmissions of the sidelink transmission (e.g., the sidelinktraffic/data). Thus, the SCI may include a respective PSSCH resourcereservation and assignment for one or more retransmissions of the PSSCH.For example, the SCI may include a reservation message indicating thePSSCH resource reservation for the initial sidelink transmission(initial PSSCH) and one or more additional PSSCH resource reservationsfor one or more retransmissions of the PSSCH.

FIGS. 4A and 4B are diagrams illustrating examples of sidelink slotstructures according to some aspects. The sidelink slot structures maybe utilized, for example, in a V2X or other D2D network implementingsidelink In the examples shown in FIGS. 4A and 4B, time is in thehorizontal direction with units of symbols 402 (e.g., OFDM symbols); andfrequency is in the vertical direction. Here, a carrier bandwidth 404allocated for sidelink wireless communication is illustrated along thefrequency axis. The carrier bandwidth 404 may include a plurality ofsub-channels, where each sub-channel may include a configurable numberof PRBs (e.g., 10, 15, 20, 25, 50, 75, or 100 PRBs).

Each of FIGS. 4A and 4B illustrate an example of a respective slot 400 aor 400 b including fourteen symbols 402 that may be used for sidelinkcommunication. However, it should be understood that sidelinkcommunication can be configured to occupy fewer than fourteen symbols ina slot 400 a or 400 b, and the disclosure is not limited to anyparticular number of symbols 402. Each sidelink slot 400 a and 400 bincludes a physical sidelink control channel (PSCCH) 406 occupying acontrol region 418 of the slot 400 a and 400 b and a physical sidelinkshared channel (PSSCH) 408 occupying a data region 420 of the slot 400 aand 400 b. The PSCCH 406 and PSSCH 408 are each transmitted on one ormore symbols 402 of the slot 400 a. The PSCCH 406 includes, for example,SCI-1 that schedules transmission of data traffic on time—frequencyresources of the corresponding PSSCH 408. As shown in FIGS. 4A and 4B,the PSCCH 406 and corresponding PSSCH 408 are transmitted in the sameslot 400 a and 400 b. In other examples, the PSCCH 406 may schedule aPSSCH in a subsequent slot.

In some examples, the PSCCH 406 duration is configured to be two orthree symbols. In addition, the PSCCH 406 may be configured to span aconfigurable number of PRBs, limited to a single sub-channel. The PSCCHresource size may be fixed for a resource pool (e.g., 10% to 100% of onesub-channel in the first two or three symbols). For example, the PSCCH406 may occupy 10, 12, 15, 20, or 25 RBs of a single sub-channel. Ineach of the examples shown in FIGS. 4A and 4B, the starting symbol forthe PSCCH 406 is the second symbol of the corresponding slot 400 a or400 b and the PSCCH 406 spans three symbols 402. The PSCCH 406 mayfurther include DMRSs.

The PSSCH 408 may be time-division multiplexed (TDMed) with the PSCCH406 and/or frequency-division multiplexed (FDMed) with the PSCCH 406. Inthe example shown in FIG. 4A, the PSSCH 408 includes a first portion 408a that is TDMed with the PSCCH 406 and a second portion 408 b that isFDMed with the PSCCH 406. In the example shown in FIG. 4B, the PSSCH 408is TDMed with the PSCCH 406.

One and two layer transmissions of the PSSCH 408 may be supported withvarious modulation orders (e.g., QPSK, 16-QAM, 64-QAM and 256-QAM). Inaddition, the PSSCH 408 may include DMRSs 414 configured in a two,three, or four symbol DMRS pattern. For example, slot 400 a shown inFIG. 4A illustrates a two symbol DMRS pattern, while slot 400 b shown inFIG. 4B illustrates a three symbol DMRS pattern. In some examples, thetransmitting UE can select the DMRS pattern and indicate the selectedDMRS pattern in SCI-1, according to channel conditions. The DMRS patternmay be selected, for example, based on the number of PSSCH 408 symbolsin the slot 400 a or 400 b. In some examples, the DMRSs 414 may be basedon a Gold sequence and a configuration type 1 may be used for thefrequency domain pattern of the PSSCH DMRSs 414. In addition, a gapsymbol 416 is present after the PSSCH 408 in each slot 400 a and 400 b.

Each slot 400 a and 400 b further includes SCI-2 412 mapped tocontiguous RBs in the PSSCH 408 starting from the first symbolcontaining a PSSCH DMRS. In the example shown in FIG. 4A, the firstsymbol containing a PSSCH DMRS is the fifth symbol occurring immediatelyafter the last symbol carrying the PSCCH 406. Therefore, the SCI-2 412is mapped to RBs within the fifth symbol. In the example shown in FIG.4B, the first symbol containing a PSSCH DMRS is the second symbol, whichalso includes the PSCCH 406. In addition, the SCI-2/PSSCH DMRS 412 areshown spanning symbols two through five. As a result, the SCI-2/PSSCHDMRS 412 may be FDMed with the PSCCH 406 in symbols two through four andTDMed with the PSCCH 406 in symbol five.

The SCI-2 may be scrambled separately from the sidelink shared channel.In addition, the SCI-2 may utilize QPSK. When the PSSCH transmissionspans two layers, the SCI-2 modulation symbols may be copied on (e.g.,repeated on) both layers. The SCI-1 in the PSCCH 406 may be blinddecoded at the receiving wireless communication device. However, sincethe format, starting location, and number of REs of the SCI-2 412 may bederived from the SCI-1, blind decoding of SCI-2 is not needed at thereceiver (receiving UE).

In each of FIGS. 4A and 4B, the second symbol of each slot 400 a and 400b is copied onto (repeated on) a first symbol 410 thereof for automaticgain control (AGC) settling. For example, in FIG. 4A, the second symbolcontaining the PSCCH 406 FDMed with the PSSCH 408 b may be transmittedon both the first symbol and the second symbol. In the example shown inFIG. 4B, the second symbol containing the PSCCH 406 FDMed with theSCI-2/PSSCH DMRS 412 may be transmitted on both the first symbol and thesecond symbol.

FIG. 5 is a diagram illustrating an example of a sidelink slot structurewith feedback resources according to some aspects. The sidelink slotstructure may be utilized, for example, in a V2X or other D2D networkimplementing sidelink In the example shown in FIG. 5 , time is in thehorizontal direction with units of symbols 502 (e.g., OFDM symbols); andfrequency is in the vertical direction. Here, a carrier bandwidth 504allocated for sidelink wireless communication is illustrated along thefrequency axis. A slot 500 having the slot structure shown in FIG. 5includes fourteen symbols 502 that may be used for sidelinkcommunication. However, it should be understood that sidelinkcommunication can be configured to occupy fewer than fourteen symbols ina slot 500, and the disclosure is not limited to any particular numberof symbols 502.

As in the examples shown in FIGS. 4A and 4B, the sidelink slot 500includes a PSCCH 506 occupying a control region of the slot 500 and aPSSCH 508 occupying a data region of the slot 500. The PSCCH 506 andPSSCH 508 are each transmitted on one or more symbols 502 of the slot500. The PSCCH 506 includes, for example, SCI-1 that schedulestransmission of data traffic on time—frequency resources of thecorresponding PSSCH 508. As shown in FIG. 5 , the starting symbol forthe PSCCH 506 is the second symbol of the slot 500 and the PSCCH 506spans three symbols 502. The PSSCH 508 may be time-division multiplexed(TDMed) with the PSCCH 506 and/or frequency-division multiplexed (FDMed)with the PSCCH 506. In the example shown in FIG. 5 , the PSSCH 508includes a first portion 508 a that is TDMed with the PSCCH 506 and asecond portion 508 b that is FDMed with the PSCCH 506.

The PSSCH 508 may further include DMRSs 514 configured in a two, three,or four symbol DMRS pattern. For example, slot 500 shown in FIG. 5illustrates a two symbol DMRS pattern. In some examples, thetransmitting UE can select the DMRS pattern and indicate the selectedDMRS pattern in SCI-1, according to channel conditions. The DMRS patternmay be selected, for example, based on the number of PSSCH 508 symbolsin the slot 500. In some examples, the DMRSs 514 may be based on a Goldsequence and a configuration type 1 may be used for the frequency domainpattern of the PSSCH DMRSs 514. In addition, a gap symbol 516 is presentafter the PSSCH 508 in the slot 500.

The slot 500 further includes SCI-2 512 mapped to contiguous RBs in thePSSCH 508 starting from the first symbol containing a PSSCH DMRS. In theexample shown in FIG. 5 , the first symbol containing a PSSCH DMRS isthe fifth symbol occurring immediately after the last symbol carryingthe PSCCH 506. Therefore, the SCI-2 512 is mapped to RBs within thefifth symbol.

In addition, as shown in FIG. 5 , the second symbol of the slot 500 iscopied onto (repeated on) a first symbol 510 thereof for automatic gaincontrol (AGC) settling. For example, in FIG. 5 , the second symbolcontaining the PSCCH 506 FDMed with the PSSCH 508 b may be transmittedon both the first symbol and the second symbol.

HARQ feedback may further be transmitted on a physical sidelink feedbackchannel (PSFCH) 518 in a configurable resource period of 0, 1, 2, or 4slots. In sidelink slots (e.g., slot 500) containing the PSFCH 518, onesymbol 502 may be allocated to the PSFCH 518, and the PSFCH 518 may becopied onto (repeated on) a previous symbol for AGC settling. In theexample shown in FIG. 5 , the PSFCH 518 is transmitted on the thirteenthsymbol and copied onto the twelfth symbol in the slot 500. A gap symbol516 may further be placed after the PSFCH symbols 518.

In some examples, there is a mapping between the PSSCH 508 and thecorresponding PSFCH resource. The mapping may be based on, for example,the starting sub-channel of the PSSCH 508, the slot containing the PSSCH508, the source ID and the destination ID. In addition, the PSFCH can beenabled for unicast and groupcast communication. For unicast, the PSFCHmay include one ACK/NACK bit. For groupcast, there may be two feedbackmodes for the PSFCH. In a first groupcast PSFCH mode, the receiving UEtransmits only NACK, whereas in a second groupcast PSFCH mode, thereceiving UE may transmit either ACK or NACK. The number of availablePSFCH resources may be equal to or greater than the number of UEs in thesecond groupcast PSFCH mode.

In response to receiving a NACK, the transmitting UE may send a HARQretransmission, which may implement chase combining (HARQ-CC) orincremental redundancy (HARQ-IR). In HARQ-CC, a retransmitted encodedcode block (e.g., an encoded packet) is identical to the originaltransmission. That is, if an encoded code block is not decoded properlyat the receiving sidelink device, resulting in a NACK, then thetransmitting sidelink device may retransmit the full encoded code blockincluding identical information to the original transmission. Theinformation may then ideally be obtained error-free by virtue of aprocess called soft combining, where the redundant bits from theretransmission may be combined before decoding to increase theprobability of correct reception of each bit. On the other hand, inHARQ-IR, the retransmitted encoded code block may be different from theoriginally transmitted encoded code block, and further, if multipleretransmissions are made, each retransmission may differ from oneanother. Here, retransmissions may include different sets of coded bits:for example, corresponding to different code rates or algorithms;corresponding to different portions of the original code block, some ofwhich may not have been transmitted in the original transmission;corresponding to forward error correction (FEC) bits that were nottransmitted in the original transmission; or other suitable schemes. Aswith HARQ-CC, here, the information may be obtained error-free byutilizing soft combining to combine the retransmitted bits with theoriginal transmitted bits.

In various aspects of the disclosure, instead of the transmitting UEinitiating one or more retransmissions of the packet based on receivinga NACK, the retransmissions may be turned over to a network codingdevice in the sidelink network. For example, the transmitting UE maytransmit an initial sidelink transmission of a packet over a PSSCH toone or more receiving UEs and a network coding device. The networkcoding device may then retransmit the packet to the one or morereceiving UEs as a network coded sidelink transmission. In someexamples, the network coded sidelink transmission may include the packetand one or more additional packets initially transmitted by other UEs.

FIG. 6 is a diagram illustrating an example of initial sidelinktranmissions by transmitting UEs (e.g., V-UEs) 602 and 604 to receivingUEs (e.g., V-UEs) 606 and 608 for network coding in a sidelink network600 according to some aspects. Although UEs 602-608 are illustrated asV-UEs, each of the UEs 602-608 may correspond to any of the UEs,sidelink devices, D2D devices, or other scheduled entities illustratedin FIGS. 1 and/or 3 .

In the example shown in FIG. 6 , the transmitting UE 602 transmits aninitial sidelink transmission Tx_(a) to the receiving UEs 606 and 608.In addition, the transmitting UE 604 transmits an initial sidelinktransmission Tx_(b) to the receiving UEs 606 and 608. In some examples,each of the initial sidelink transmissions Tx_(a) and Tx_(b) may begroupcast or broadcast transmissions.

The initial sidelink transmission Tx_(a) is successfully received anddecoded by the receiving UE 606. Thus, the receiving UE 606 may transmitan ACK (or not transmit a NACK) to the transmitting UE 602 However, theinitial sidelink transmission Tx_(a) is not successfully received anddecoded by the receiving UE 608, resulting in the receiving UE 608transmitting a NACK to the transmitting UE 602. In addition, the initialsidelink transmission Tx_(b) is successfully received and decoded by thereceiving UE 608. As such, the receiving UE 608 may transmit an ACK (ornot transmit a NACK) to the transmitting UE 604. However, the initialsidelink transmission Tx_(b) is not successfully received and decoded bythe receiving UE 606, resulting in the receiving UE 606 transmitting aNACK to the transmitting UE 604.

Each of the initial sidelink transmissions Tx_(a) and Tx_(b) may furtherbe transmitted to a network coding device 610. The network coding device610 may be, for example, an RSU, another UE, or a base station (e.g.,gNB). For example, each of the initial sidelink transmissions Tx_(a) andTx_(b) may include a network coding request flag requesting networkcoding of the respective sidelink transmissions Tx_(a) and Tx_(b) by thenetwork coding device 610. Upon successfully receiving and decoding theinitial sidelink transmissions Tx_(a) and Tx_(b), the network codingdevice 610 may transmit a respective network coding accept requestmessage to each of the transmitting UEs 602 and 604. The network codingaccept request messages may correspond, for example, to an ACK of thesidelink transmissions Tx_(a) and Tx_(b).

The network coding device 610 may then initiate one or moreretransmissions of the sidelink transmissions Tx_(a) and Tx_(b). In someexamples, the network coding device 610 may initiate sidelinkretransmissions regardless of whether one or more of the receiving UEs606 and 608 NACKed either or both of the initial sidelink transmissionsTx_(a) and Tx_(b). In other examples, the network coding device 610 mayinitiate sidelink retransmissions upon receiving at least one NACK ofone or both of the initial sidelink transmissions Tx_(a) and Tx_(b).

FIG. 7 is a diagram illustrating an example of a network coded sidelinktransmission in a sidelink network 700 according to some aspects. In theexample shown in FIG. 7 , the sidelink network 700 includes originaltransmitting UEs (e.g., V-UEs) 702 and 704, which may correspond, forexample, to transmitting UEs 602 and 604 shown in FIG. 6 . In addition,the sidelink network 700 includes receiving UEs (e.g., V-UEs) 706 and708, which may correspond, for example, to receiving UEs 606 and 608shown in FIG. 6 . The sidelink network 700 further includes a networkcoding device 710, which may correspond, for example, to the networkcoding device 610 shown in FIG. 6 .

The network coding device 710 may be configured to retransmit sidelinktransmissions Tx_(a) and Tx_(b) received from the transmitting UEs 702and 704 (e.g., as shown in FIG. 6 ) as a network coded sidelinktransmission. In some examples, the network coded sidelink transmissionmay be a function (e.g., XOR) of each of the initial sidelinktransmissions (f(Tx_(a), Tx_(b))). In some examples, the network codingdevice 710 may utilize erasure coding as the function to generate thenetwork coded sidelink transmission. With erasure coding, a receiving UE(e.g., UE 706) may recover an erased (incorrectly decoded) transmissionby summing the other correctly decoded transmissions. For example, ifthe network coded sidelink transmission corresponds to Tx_(a)⊕Tx_(b) andthe receiving UE 706 previously correctly decoded Tx_(a), the receivingUE 706 can recover the erased Tx_(b) by summing Tx_(a) with the networkcoded sidelink transmission Tx_(a)⊕Tx_(b) as follows:Tx_(a)⊕(Tx_(a)⊕Tx_(b)). The network coding device 710 may furtherutilize any type of channel coding for subsequently encoding the networkcoded sidelink transmission. By way of example, but not limitation, thenetwork coding device 710 may utilize turbo coding, low density paritycheck (LDPC) coding, polar coding, etc. to encode the network codedsidelink transmission.

The receiving UEs 706 and 708 may receive the network coded sidelinktransmission and attempt to decode the initial sidelink transmission(s)(e.g., Tx_(a) and/or Tx_(b)) based on the network coded sidelinktransmission. Using the example shown in FIG. 6, the receiving UE 606may be able to decode Tx_(b) from the network coded sidelinktransmission (f(Tx_(a), Tx_(b))) and the originally decoded initialsidelink transmission Tx_(a). In addition, the receiving UE 608 may beable to decode Tx_(a) from the network coded sidelink transmission(f(Tx_(a), Tx_(b))) and the originally decoded initial sidelinktransmission Tx_(b).

In some examples, utilizing the network coding device 710 to perform theretransmissions of sidelink packets may increase the reliability of thesidelink packets. For example, the network coding device 710 may beconfigured to perform more retransmissions than the transmitting UEs 702and 704. In various aspects, the gain in reliability achieved by networkcoding may be leveraged to increase the spectral efficiency of theinitial sidelink transmission by the transmitting UE. For example, thetransmitting UEs 702 and 704 may each encode their respective initialsidelink transmissions Tx_(a) and Tx_(b) using a higher MCS than anormal MCS that may be used without network coding. By using a higherMCS, the initial sidelink transmission may utilize fewer resources inthe frequency domain, thus reducing congestion. As a result, more UEsmay be allowed to transmit within the same time resources and/or theprobability of colliding transmissions between UEs may be reduced.

FIGS. 8A and 8B are diagrams illustrating exemplary feedback for initialsidelink transmissions and network coded sidelink transmissionsaccording to some aspects. FIG. 8A illustrates a table 800 maintained bya network coding device of a plurality of packets (e.g., transportblocks (TBs)) 802, each intended for receipt by plurality of receivingUEs (Rx UEs) 804. In the example shown in FIG. 8A, there are fourpackets 802 (e.g., p₀, p₁, p₂, and p₃). Each packet 802 is initiallytransmitted to four Rx UEs (e.g., UE₀, UE₁, UE₂, and UE₃). The packets802 may be transmitted by the same transmitting UE (Tx UE) or bydifferent Tx UEs. The table 800 is populated with feedback information806 for each of the packets 802 by each of the Rx UEs 804. For example,the table 800 may include feedback information 806 indicating that UE₀transmitted an acknowledgement (ACK) transmitted for packets p₀ and p₂and a negative acknowledgement (NACK) for packet p₁. An empty cell 808in the table 800 indicates that no feedback information was received bythe network coding device from a particular UE for a particular packet802.

FIG. 8B illustrates a table 810 maintained by the network coding deviceof a plurality of network coded packets 812 that may be transmitted tothe plurality of Rx UEs 804. In the example shown in FIG. 8B, eachnetwork coded packet 812 is a function of two of the initiallytransmitted packets 802 shown in FIG. 8A (e.g., p₀+p₁, p₀+p₂, p₀+p₃,p₁+p₂, p₁+p₃, and p₂+p₃). A checkmark 814 in a cell of the table 810indicates that a particular UE may be able to decode a previouslyundecoded packet from the network coded packet 812, a “D” in a cellindicates that a particular UE previously decoded both of the initiallytransmitted packets 802 in the network coded packet 812, and an “X” in acell indicates that a particular UE was unable to decode either of theinitially transmitted packets 802 (e.g., based on the network codingdevice receiving a NACK or no feedback), and therefore, that UE willalso be unable to decode the network coded packet 812.

The network coding device may utilize the table 810 to select thenetwork coded packet 812 that maximizes the number of potential NACK toACK flips. In the example shown in FIG. 8 , the first network codedpacket 812 (e.g., p₀+p₁) in the table 810 may enable three of the UEs804 to decode a previously undecoded packet. For example, U₀ and UE₃ mayeach be able to decode packet p₁ from the p₀+p₁ network coded packet812. In addition, UE₂ may be able to decode packet p₀ from the p₀+p₁network coded packet 812. Therefore, the network coding device mayselect the p₀+p₁ network coded packet 812 as the first network codedpacket transmitted to the plurality of UEs 804 since the p₀+p₁ networkcoded packet 812 may result in three NACK to ACK flips (e.g., UE₀, UE₂,and UE₃).

FIG. 9 is a diagram illustrating exemplary signaling 900 for sidelinknetwork coding by a network coding device 906 of a sidelink transmissioninitially transmitted from a Tx UE 902 to an Rx UE 904 according to someaspects. The Tx UE 902 and Rx UE 904 may correspond to any of the UEs,sidelink devices, V2X devices, D2D devices, or other scheduled entitiesillustrated in any of FIGS. 1, 3, 6 and/or 7 . In some examples, the RxUE 904 may represent one or more Rx UEs of an initial sidelinktransmission by the Tx UE 902. The network coding device 906 maycorrespond to the network coding devices shown in FIGS. 6 and/or 7 andmay include, for example, an RSU, another UE, or a gNB. In someexamples, the network coding device 906 may be one of the destinationUEs for the initial sidelink transmission.

At a first time (t₁), the Tx UE 902 may transmit an initial sidelinktransmission 908 including a packet 910 and a network coding requestflag 912. In some examples, the initial sidelink transmission 908 may betransmitted over a sidelink data channel (e.g., a PSSCH) and the networkcoding request flag may be transmitted over a sidelink control channel(e.g., via SCI within a PSCCH). For example, the network coding requestflag may include a single bit within SCI-1 carrying the PSSCH resourceassignment for the encoded packet or within SCI-2 associated with thePSSCH. The initial sidelink transmission including the encoded packetand network coding request flag may be received by the network codingdevice 906 and may further be received by one or more Rx UEs 904 (onlyone of which is shown for convenience) to which the packet is destined.For example, the initial sidelink transmission 908 may be a unicast,groupcast, or broadcast transmission destined for one or more Rx UEs904.

At a second time (t₂), the Rx UE 904 (and each other Rx UE to which theinitial sidelink transmission 908 is destined) may transmit feedbackinformation 914 (e.g., HARQ ACK/NACK) to the Tx UE 902 indicatingwhether the Rx UE 904 was able to successfully decode the packet. Inaddition, at the second time (t₂), the network coding device 906 maytransmit a network coding accept request message 916 to the Tx UE 902 toindicate whether the network coding device 906 will perform networkcoding of the packet. In some examples, the accept request message 916may correspond to an ACK of the initial sidelink transmission.

At a third time (t₃), the network coding device 906 may retransmit thepacket as a network coded sidelink transmission to the one or more RxUEs 904. In some examples, the network coded sidelink transmission maybe a function (e.g., XOR) of the packet 910 and one or more otherpackets transmitted by the same Tx UE 902 or another Tx UE to the one ormore Rx UEs 904.

In half-duplex communication, the frequencies utilized for transmissionand reception are the same. Therefore, a wireless communication device(e.g., the network coding device 906) may be constrained fromtransmitting and receiving at the same time. This constraint is referredto herein as a half-duplex (HD) constraint. Because of the HDconstraint, the network coding device 906 may not receive the feedbackinformation 914 transmitted from the Rx UE 904 to the Tx UE 902 sincethe network coding device 906 is transmitting the accept request message916 at the same time (e.g., time t₂, which may correspond, for example,to a slot). As indicated in FIGS. 8A and 8B, receipt of the feedbackinformation 914 may improve network coded sidelink transmissions byenabling the network coding device 906 to select the packets forretransmission that maximize NACK to ACK flips. Therefore, in variousaspects of the disclosure, the network coding device 906 may staggertransmission of the accept request message 916 relative to the feedbackinformation 914 to enable receipt of the feedback information 914 by thenetwork coding device 906.

In some examples, the accept request message 916 may be delayed withrespect to the feedback information 914. In this example, the acceptrequest message 916 may be transmitted at a time that is subsequent to(e.g., later than) than the time at which the feedback information 914is transmitted. In other examples, the accept request message 916 may besent in advance of (e.g., prior to) the feedback information 914. Inthis example, the accept request message 915 may be transmitted at atime that is earlier than (e.g., prior to) the time at which thefeedback information 914 is transmitted.

FIG. 10 is a diagram illustrating exemplary signaling 1000 for delayingaccept request messages in sidelink network coding according to someaspects. FIG. 10 illustrates signaling 1000 between a Tx UE 1002, an RxUE 1004 and a network coding device 1006. The Tx UE 1002 and Rx UE 1004may correspond to any of the UEs, sidelink devices, V2X devices, D2Ddevices, or other scheduled entities illustrated in any of FIGS. 1, 3,6, 7 , and/or 9. In some examples, the Rx UE 1004 may represent one ormore Rx UEs of an initial sidelink transmission by the Tx UE 1002. Thenetwork coding device 1006 may correspond to the network coding devicesshown in FIGS. 6, 7 and/or 9 and may include, for example, an RSU,another UE, or a gNB. In some examples, the network coding device 1006may be one of the Rx UEs.

At a first time (t₁), the Tx UE 1002 may transmit an initial sidelinktransmission 1008 including a packet 1010 and a network coding requestflag 1012. In some examples, the initial sidelink transmission 1008 maybe transmitted over a sidelink data channel (e.g., a PSSCH) and thenetwork coding request flag may be transmitted over a sidelink controlchannel (e.g., via SCI within a PSCCH). For example, the network codingrequest flag may include a single bit within SCI-1 carrying the PSSCHresource assignment for the encoded packet or within SCI-2 associatedwith the PSSCH. The initial sidelink transmission including the encodedpacket and network coding request flag may be received by the networkcoding device 1006 and may further be received by one or more Rx UEs1004 (only one of which is shown for convenience) to which the packet isdestined. For example, the initial sidelink transmission 1008 may be aunicast, groupcast, or broadcast transmission destined for one or moreRx UEs 1004.

At a second time (t₂), the Rx UE 1004 (and each other Rx UE to which theinitial sidelink transmission 1008 is destined) may transmit feedbackinformation 1014 (e.g., HARQ ACK/NACK) to the Tx UE 1002 indicatingwhether the Rx UE 1004 was able to successfully decode the packet. Thefeedback information 1014 may further be received by the network codingdevice 1006.

At a third time (t₃), the network coding device 1006 may transmit anetwork coding accept request message 1016 to the Tx UE 1002 to indicatewhether the network coding device 1006 will perform network coding ofthe packet. In an aspect, the network coding device 1006 may delaytransmission of the accept request message 1016 by a duration of time1020 between the receipt of the feedback information 1014 at time t₂ andtransmission of the accept request message 1016 at time t₃ to enablereceipt of the feedback information 1014 at time t₂ by the networkcoding device 1006. In some examples, the duration of time 1020 maycorrespond to a number of slots, which may be fixed or variable. Forexample, the number of slots between receipt of the feedback information1014 and transmission of the accept request message 1016 may bepre-configured (e.g., via the original equipment manufacturer (OEM)based on, for example, one or more sidelink standards or specificationsor via radio resource control (RRC) signaling by a base station) orconfigured by the network coding device 1006 and sent to the Tx UE 1002.In some examples, the maximum number of slots that may be configured maybe dependent upon one or more parameters. Examples of parametersinclude, but are not limited to, a priority of the packet 1010 or apacket delay budget (PDB) associated with the packet 1010.

In some examples, the duration of time 1020 may be based on a timer. Forexample, the network coding device 1006 may initiate (set) a timer uponreceipt of the sidelink transmission 1008 from the Tx UE 1002. The timermay have a timer duration 1022 configured to produce a delay betweenreceipt of the feedback information 1014 and transmission of the acceptrequest message 1016 corresponding to the duration of time 1020. In thisexample, the network coding device 1006 may transmit the accept requestmessage 1016 upon expiration of the timer. In some examples, the timerduration 1022 may be pre-configured (e.g., via the original equipmentmanufacturer (OEM) based on, for example, one or more sidelink standardsor specifications or via radio resource control (RRC) signaling by abase station) or configured by the network coding device 1006 and sentto the Tx UE 1002. In some examples, the timer duration may be dependentupon one or more parameters. Examples of parameters include, but are notlimited to, a priority of the packet 1010 or a packet delay budget (PDB)associated with the packet 1010.

In some examples, the network coding device 1006 may lock the timer uponreceipt of the first sidelink transmission 1008 that includes a networkcoding request flag 1012. As a result, the network coding device 1006may use a single timer for the first sidelink transmission 1008 and allsubsequent sidelink transmissions that include network coding requestflags 1012 received prior to expiration of the timer. In this example,the network coding device may combine the accept request messages foreach of the sidelink transmissions received during the timer duration1022 and transmit a combined accept request message including the acceptrequest message 1016 for the Tx UE 1002 upon expiration of the timer.

At a fourth time (t₄), the network coding device 1006 may retransmit thepacket as a network coded sidelink transmission to the one or more RxUEs 1004. In some examples, the network coded sidelink transmission maybe a function (e.g., XOR) of the packet 1010 and one or more otherpackets transmitted by the same Tx UE 1002 or another Tx UE to the oneor more Rx UEs 1004.

FIG. 11 is a flow chart illustrating an exemplary process 1100 forslot-based delay of accept request messages in sidelink network codingaccording to some aspects. As described below, some or all illustratedfeatures may be omitted in a particular implementation within the scopeof the present disclosure, and some illustrated features may not berequired for implementation of all examples. In some examples, themethod may be performed by the network coding device 1800, as describedbelow and illustrated in FIG. 18 , by a processor or processing system,or by any suitable means for carrying out the described functions.

At block 1102, the network coding device may receive an initial sidelinktransmission from a Tx UE including a packet and a network codingrequest flag. In some examples, the initial sidelink transmission may betransmitted over a sidelink data channel (e.g., a PSSCH) and the networkcoding request flag may be transmitted over a sidelink control channel(e.g., via SCI within a PSCCH). For example, the network coding requestflag may include a single bit within SCI-1 carrying the PSSCH resourceassignment for the encoded packet or within SCI-2 associated with thePSSCH. The initial sidelink transmission including the encoded packetand network coding request flag may be received by the network codingdevice and may further be received by one or more Rx UEs to which thepacket is destined. For example, the initial sidelink transmission maybe a unicast, groupcast, or broadcast transmission destined for one ormore Rx UEs.

At block 1104, the network coding device may identify a number of slotsbetween receipt of the initial sidelink transmission that includes thenetwork coding request flag and transmission of an accept requestmessage. In some examples, the number of slots may be pre-configured onat least the network coding device (e.g., via the OEM based on, forexample, one or more sidelink standards or specifications or via radioresource control (RRC) signaling by a base station). In other examples,the network coding device may select the number of slots. For example,the network coding device may configure the number of slots based on oneor more parameters. Examples of parameters include, but are not limitedto, a priority of the packet or a packet delay budget (PDB) associatedwith the packet.

At block 1106, the network coding device may optionally transmit thenumber of slots to the Tx UE. For example, the network coding device maytransmit the number of slots to the Tx UE when the network coding deviceconfigures the number of slots based on one or more parameters. Inexamples in which the number of slots is pre-configured on the networkcoding device, the network coding device may not transmit the number ofslots to the Tx UE. For example, if the number of slots is alsopre-configured on the Tx UE (e.g., via the OEM or RRC signaling), thenetwork coding device may not transmit the number of slots to the Tx UE.

At block 1108, the network coding device may receive feedbackinformation (e.g., HARQ ACK/NACK) for the packet from the Rx UE. Forexample, the feedback information may be transmitted from the Rx UE tothe Tx UE and further be received by the network coding device.

At block 1110, the network coding device may determine whether thenumber of slots has passed since receipt of the feedback information. Ifthe number of slots has passed (Y branch of block 1110), at block 1112,the network coding device may transmit an accept request message to theTx UE that indicates whether the network coding device acceptsperforming retransmission(s) of the packet. Thus, the network codingdevice may delay transmission of the accept request message by thenumber of slots identified by the network coding device at block 1104.As such, at block 1112, the network coding device transmits the acceptrequest message after the number of slots from receipt of the feedbackinformation.

At block 1114, the network coding device may transmit a network codedpacket including a retransmission of the packet received at block 1102.In some examples, the network coded packet may be a function (e.g., XOR)of the packet received at block 1102 and one or more other packetstransmitted by the same Tx UE or another Tx UE to the one or more RxUEs.

FIG. 12 is a flow chart illustrating an exemplary process 1200 fortimer-based staggering of accept request messages and feedbackinformation in sidelink network coding according to some aspects. Asdescribed below, some or all illustrated features may be omitted in aparticular implementation within the scope of the present disclosure,and some illustrated features may not be required for implementation ofall examples. In some examples, the method may be performed by thenetwork coding device 1800, as described below and illustrated in FIG.18 , by a processor or processing system, or by any suitable means forcarrying out the described functions.

At block 1202, the network coding device may receive an initial sidelinktransmission from a Tx UE including a packet and a network codingrequest flag. In some examples, the initial sidelink transmission may betransmitted over a sidelink data channel (e.g., a PSSCH) and the networkcoding request flag may be transmitted over a sidelink control channel(e.g., via SCI within a PSCCH). For example, the network coding requestflag may include a single bit within SCI-1 carrying the PSSCH resourceassignment for the encoded packet or within SCI-2 associated with thePSSCH. The initial sidelink transmission including the encoded packetand network coding request flag may be received by the network codingdevice and may further be received by one or more Rx UEs to which thepacket is destined. For example, the initial sidelink transmission maybe a unicast, groupcast, or broadcast transmission destined for one ormore Rx UEs.

At block 1204, the network coding device may identify a timer durationconfigured to stagger transmission of an accept request message withrespect to feedback information received from an Rx UE. In someexamples, the timer duration may be pre-configured on at least thenetwork coding device (e.g., via the OEM based on, for example, one ormore sidelink standards or specifications or via radio resource control(RRC) signaling by a base station). In other examples, the networkcoding device may select the timer duration. For example, the networkcoding device may configure the timer duration based on one or moreparameters. Examples of parameters include, but are not limited to, apriority of the packet or a packet delay budget (PDB) associated withthe packet.

At block 1206, the network coding device may set (initialize) the timerwith the timer duration. At block 1208, the network coding device mayoptionally transmit the timer duration to the Tx UE. For example, thenetwork coding device may transmit the timer duration to the Tx UE whenthe network coding device configures the timer duration based on one ormore parameters. In examples in which the timer duration ispre-configured on the network coding device, the network coding devicemay not transmit the timer duration to the Tx UE. For example, if thetimer duration is also pre-configured on the Tx UE (e.g., via the OEM orRRC signaling), the network coding device may not transmit the timerduration to the Tx UE.

At block 1210, the network coding device may receive feedbackinformation (e.g., HARQ ACK/NACK) for the packet from the Rx UE. Forexample, the feedback information may be transmitted from the Rx UE tothe Tx UE and further be received by the network coding device. In someexamples, the feedback information may be received prior to expirationof the timer (as shown in FIG. 12 ). In other examples, the feedbackinformation may be received after expiration of the timer. In thisexample, the feedback information may be received at a time that islater than the time of transmission of the accept request message.

At block 1212, the network coding device may determine whether the timerhas expired. If the timer has expired (Y branch of block 1212), at block1214, the network coding device may transmit an accept request messageto the Tx UE that indicates whether the network coding device acceptsperforming retransmission(s) of the packet. Thus, the timer duration maybe configured to produce a delay between receipt of the feedbackinformation at block 1210 and transmission of the accept request messageat block 1214.

At block 1216, the network coding device may transmit a network codedpacket including a retransmission of the packet received at block 1202.In some examples, the network coded packet may be a function (e.g., XOR)of the packet received at block 1202 and one or more other packetstransmitted by the same Tx UE or another Tx UE to the one or more RxUEs.

FIG. 13 is a flow chart illustrating an exemplary process 1300 fortimer-based delay of multiple accept request messages in sidelinknetwork coding according to some aspects. As described below, some orall illustrated features may be omitted in a particular implementationwithin the scope of the present disclosure, and some illustratedfeatures may not be required for implementation of all examples. In someexamples, the method may be performed by the network coding device 1800,as described below and illustrated in FIG. 18 , by a processor orprocessing system, or by any suitable means for carrying out thedescribed functions.

At block 1302, the network coding device may receive a first sidelinktransmission from a first Tx UE including a first packet and a networkcoding request flag. In some examples, the first sidelink transmissionmay be transmitted over a sidelink data channel (e.g., a PSSCH) and thenetwork coding request flag may be transmitted over a sidelink controlchannel (e.g., via SCI within a PSCCH). For example, the network codingrequest flag may include a single bit within SCI-1 carrying the PSSCHresource assignment for the encoded packet or within SCI-2 associatedwith the PSSCH. The first sidelink transmission including the encodedpacket and network coding request flag may be received by the networkcoding device and may further be received by one or more Rx UEs to whichthe packet is destined. For example, the initial sidelink transmissionmay be a unicast, groupcast, or broadcast transmission destined for oneor more Rx UEs.

At block 1304, the network coding device may set a timer upon receipt ofthe first sidelink transmission. In some examples, the timer isinitialized with a timer duration configured to delay transmission of anaccept request message for the first sidelink transmission with respectto feedback information received for the sidelink transmission. Thetimer duration may be pre-configured (e.g., via the original equipmentmanufacturer (OEM) based on, for example, one or more sidelink standardsor specifications or via radio resource control (RRC) signaling by abase station) or configured by the network coding device.

At block 1306, the network coding device may generate an accept requestmessage for the first packet. In some examples, the accept requestmessage may include a packet identifier identifying the packet, a sourceidentifier (e.g., a UE ID) identifying the first Tx UE, and a networkcoding indicator (e.g., a single bit) indicating whether the networkcoding device accepts performing retransmission(s) of the first packet.

At block 1308, the network coding device may determine whether the timerhas expired. If the timer has not expired (N branch of block 1308), atblock 1310, the network coding device may receive one or more additionalsidelink transmissions, each including a respective additional packetand a respective additional network coding request from the same firstTx UE or another Tx UE prior to expiration of the timer. For eachadditional sidelink transmission received by the network coding device,the network coding device may generate a respective accept requestmessage for the respective packet at block 1306.

Once the timer expires (Y branch of block 1308), at block 1312, thenetwork coding device may combine the accept request messages to producea combined accept request message. At block 1314, the network codingdevice may then transmit the combined accept request message to theplurality of Tx UEs (including the first Tx UE) that sent sidelinktransmissions including network coding request flags during the timerduration. The combined accept request message may be, for example,groupcasted or multicasted to the plurality of Tx UEs.

FIG. 14 is a diagram illustrating exemplary signaling for includingaccept request messages within network coded sidelink transmissionsaccording to some aspects. FIG. 14 illustrates signaling between a Tx UE1402, an Rx UE 1404 and a network coding device 1406. The Tx UE 1402 andRx UE 1404 may correspond to any of the UEs, sidelink devices, V2Xdevices, D2D devices, or other scheduled entities illustrated in any ofFIGS. 1, 3, 6, 7, 9 and/or 10 . In some examples, the Rx UE 1404 mayrepresent one or more Rx UEs of an initial sidelink transmission by theTx UE 1402. The network coding device 1406 may correspond to the networkcoding devices shown in FIGS. 6, 7, 9 and/or 10 and may include, forexample, an RSU, another UE, or a gNB. In some examples, the networkcoding device 1406 may be one of the Rx UEs.

At a first time (t₁), the Tx UE 1402 may transmit an initial sidelinktransmission 1408 including a packet 1410 and a network coding requestflag 1412. In some examples, the initial sidelink transmission 1408 maybe transmitted over a sidelink data channel (e.g., a PSSCH) and thenetwork coding request flag may be transmitted over a sidelink controlchannel (e.g., via SCI within a PSCCH). For example, the network codingrequest flag may include a single bit within SCI-1 carrying the PSSCHresource assignment for the encoded packet or within SCI-2 associatedwith the PSSCH. The initial sidelink transmission including the encodedpacket and network coding request flag may be received by the networkcoding device 1406 and may further be received by one or more Rx UEs1404 (only one of which is shown for convenience) to which the packet isdestined. For example, the initial sidelink transmission 1408 may be aunicast, groupcast, or broadcast transmission destined for one or moreRx UEs 1404.

At a second time (t₂), the Rx UE 1404 (and each other Rx UE to which theinitial sidelink transmission 1408 is destined) may transmit feedbackinformation 1414 (e.g., HARQ ACK/NACK) to the Tx UE 1402 indicatingwhether the Rx UE 1404 was able to successfully decode the packet. Thefeedback information 1414 may further be received by the network codingdevice 1406.

At a third time (t₃), the network coding device 1406 may transmit anetwork coded sidelink transmission 1416 including a network codedpacket 1418 and an accept request message 1420 that indicates whetherthe network coding device 1406 will perform network coding of the packet1410. In an aspect, the network coding device 1406 may delaytransmission of the accept request message 1420 by a duration of time1422 between the receipt of the feedback information 1414 at time t₂ andtransmission of the accept request message 1420 at time t₃ to enablereceipt of the feedback information 1414 at time t₂ by the networkcoding device 1406. In some examples, the duration of time 1422 maycorrespond to the time between receipt of the feedback information 1414and the next scheduled network coded sidelink transmission 1416.

In some examples, the network coded sidelink transmission may betransmitted to the one or more Rx UEs 1404 and the Tx UE 1402. In someexamples, the network coded packet 1418 may be a function (e.g., XOR) ofthe packet 1410 and one or more other packets transmitted by the same TxUE 1402 or another Tx UE to the one or more Rx UEs 1404. In otherexamples, the network coded packet 1418 may be a function (e.g., XOR) ofother packets excluding the packet 1410 received from the Tx UE 1402. Inthis example, the accept request message 1420 may indicate that thenetwork coding device 1406 does not accept retransmission(s) of thepacket 1410 (e.g., will not perform network coding of the packet 1410).

FIG. 15 is a diagram illustrating an exemplary network coded sidelinktransmission 1500 according to some aspects. The network coded sidelinktransmission 1500 includes a network coded packet 1502 and an acceptrequest message 1504. The network coded packet 1502 includes a function(e.g., XOR) of two or more packets retransmitted by a network codingdevice. The accept request message 1504 includes an identifier (e.g., asource ID or Tx UE ID) 1506 of the Tx UE that transmitted a packet tothe network coding device including a network coding request flagrequesting the network coding device perform retransmissions of thepacket. In addition, the accept request message 1504 includes a packetidentifier (ID) 1508 identifying the packet transmitted by the Tx UE.The accept request message 1504 further includes a network codingindicator (NC indicator) 1510 indicating whether the network codingdevice accepts performing retransmission(s) of the packet. In someexamples, the network coded packet 1502 includes a retransmission of thepacket associated with the accept request message 1504. In otherexamples, the network coded packet includes retransmissions of otherpackets. In this example, the NC indicator 1510 may indicate that thenetwork coding device does not accept retransmission(s) of the packet.

In some examples, the accept request message 1504 may be transmittedwithin SCI-2, within a MAC-CE or a MAC header of the network codedsidelink transmission 1500. The network coded sidelink transmission 1500may further include SCI-1 1512 including an accept request indicator (ARIndicator) 1514 indicating that the network coded sidelink transmission1500 includes the accept request message 1504. In some examples, the ARindicator 1514 is a single bit that indicates whether or not the acceptrequest message 1504 is included. In some examples, the AR indicator1514 may be transmitted separately from the network coded sidelinktransmission 1500 (e.g., within SCI-1 or SCI-2 of a different sidelinktransmission).

FIG. 16 is a block diagram illustrating an example of a hardwareimplementation for a wireless communication device 1600 employing aprocessing system 1614. For example, the wireless communication device1600 may correspond to a sidelink device, such as a V2X device, D2Ddevice or other UE or wireless communication device configured forsidelink communication, as shown and described above in reference toFIGS. 1, 3, 6, 7, 9, 10 , and/or 14.

The wireless communication device 1600 may be implemented with aprocessing system 1614 that includes one or more processors 1604.Examples of processors 1604 include microprocessors, microcontrollers,digital signal processors (DSPs), field programmable gate arrays(FPGAs), programmable logic devices (PLDs), state machines, gated logic,discrete hardware circuits, and other suitable hardware configured toperform the various functionality described throughout this disclosure.In various examples, the wireless communication device 1600 may beconfigured to perform any one or more of the functions described herein.That is, the processor 1604, as utilized in the wireless communicationdevice 1600, may be used to implement any one or more of the processesand procedures described below.

The processor 1604 may in some instances be implemented via a basebandor modem chip and in other implementations, the processor 1604 mayinclude a number of devices distinct and different from a baseband ormodem chip (e.g., in such scenarios as may work in concert to achieveexamples discussed herein). And as mentioned above, various hardwarearrangements and components outside of a baseband modem processor can beused in implementations, including RF-chains, power amplifiers,modulators, buffers, interleavers, adders/summers, etc.

In this example, the processing system 1614 may be implemented with abus architecture, represented generally by the bus 1602. The bus 1602may include any number of interconnecting buses and bridges depending onthe specific application of the processing system 1614 and the overalldesign constraints. The bus 1602 links together various circuitsincluding one or more processors (represented generally by the processor1604), a memory 1605, and computer-readable media (represented generallyby the computer-readable medium 1606). The bus 1602 may also linkvarious other circuits such as timing sources, peripherals, voltageregulators, and power management circuits, which are well known in theart, and therefore, will not be described any further.

A bus interface 1608 provides an interface between the bus 1602, atransceiver 1610, and one or more antennas 1630 (e.g., one or moreantenna arrays or antenna panels). The transceiver 1610 provides acommunication interface or a means for communicating with various otherapparatus over a transmission medium (e.g., air interface) via theantenna(s) 1630. Depending upon the nature of the apparatus, a userinterface 1612 (e.g., keypad, display, touch screen, speaker,microphone, control knobs, etc.) may also be provided. Of course, such auser interface 1612 is optional, and may be omitted in some examples.

The processor 1604 is responsible for managing the bus 1602 and generalprocessing, including the execution of software stored on thecomputer-readable medium 1606. The software, when executed by theprocessor 1604, causes the processing system 1614 to perform the variousfunctions described below for any particular apparatus. Thecomputer-readable medium 1606 and the memory 1605 may also be used forstoring data that is manipulated by the processor 1604 when executingsoftware. For example, the memory 1605 may store one or more of feedbackinformation (Feedback) 1616, an accept request message (Accept Request)1618, a number of slots (# of Slots) 1620, and/or a timer duration(Timer Duration) 1622, which may be used by the processor 1604 ingenerating and/or processing sidelink transmissions.

One or more processors 1604 in the processing system may executesoftware. Software shall be construed broadly to mean instructions,instruction sets, code, code segments, program code, programs,subprograms, software modules, applications, software applications,software packages, routines, subroutines, objects, executables, threadsof execution, procedures, functions, etc., whether referred to assoftware, firmware, middleware, microcode, hardware descriptionlanguage, or otherwise. The software may reside on a computer-readablemedium 1606.

The computer-readable medium 1606 may be a non-transitorycomputer-readable medium. A non-transitory computer-readable mediumincludes, by way of example, a magnetic storage device (e.g., hard disk,floppy disk, magnetic strip), an optical disk (e.g., a compact disc (CD)or a digital versatile disc (DVD)), a smart card, a flash memory device(e.g., a card, a stick, or a key drive), a random access memory (RAM), aread only memory (ROM), a programmable ROM (PROM), an erasable PROM(EPROM), an electrically erasable PROM (EEPROM), a register, a removabledisk, and any other suitable medium for storing software and/orinstructions that may be accessed and read by a computer. Thecomputer-readable medium 1606 may reside in the processing system 1614,external to the processing system 1614, or distributed across multipleentities including the processing system 1614. The computer-readablemedium 1606 may be embodied in a computer program product. By way ofexample, a computer program product may include a computer-readablemedium in packaging materials. In some examples, the computer-readablemedium 1606 may be part of the memory 1605. Those skilled in the artwill recognize how best to implement the described functionalitypresented throughout this disclosure depending on the particularapplication and the overall design constraints imposed on the overallsystem. In some examples, the computer-readable medium 1606 may beimplemented on an article of manufacture, which may further include oneor more other elements or circuits, such as the processor 1604 and/ormemory 1605.

In some aspects of the disclosure, the processor 1604 may includecircuitry configured for various functions. For example, the processor1604 may include communication and processing circuitry 1642, configuredto communicate with one or more sidelink devices (e.g., other UEs and/ora network coding device) via respective sidelinks (e.g., PC5interfaces). In addition, the communication and processing circuitry1642 may be configured to communicate with a network entity (e.g., abase station, such as s gNB or eNB) via a Uu link In some examples, thecommunication and processing circuitry 1642 may include one or morehardware components that provide the physical structure that performsprocesses related to wireless communication (e.g., signal receptionand/or signal transmission) and signal processing (e.g., processing areceived signal and/or processing a signal for transmission). Forexample, the communication and processing circuitry 1642 may include oneor more transmit/receive chains.

In some implementations where the communication involves receivinginformation, the communication and processing circuitry 1642 may obtaininformation from a component of the wireless communication device 1600(e.g., from the transceiver 1610 that receives the information via radiofrequency signaling or some other type of signaling suitable for theapplicable communication medium), process (e.g., decode) theinformation, and output the processed information. For example, thecommunication and processing circuitry 1642 may output the informationto another component of the processor 1604, to the memory 1605, or tothe bus interface 1608. In some examples, the communication andprocessing circuitry 1642 may receive one or more of signals, messages,other information, or any combination thereof. In some examples, thecommunication and processing circuitry 1642 may receive information viaone or more channels. In some examples, the communication and processingcircuitry 1642 may include functionality for a means for receiving. Insome examples, the communication and processing circuitry 1642 mayinclude functionality for a means for processing, including a means fordemodulating, a means for decoding, etc.

In some implementations where the communication involves sending (e.g.,transmitting) information, the communication and processing circuitry1642 may obtain information (e.g., from another component of theprocessor 1604, the memory 1605, or the bus interface 1608), process(e.g., modulate, encode, etc.) the information, and output the processedinformation. For example, the communication and processing circuitry1642 may output the information to the transceiver 1610 (e.g., thattransmits the information via radio frequency signaling or some othertype of signaling suitable for the applicable communication medium). Insome examples, the communication and processing circuitry 1642 may sendone or more of signals, messages, other information, or any combinationthereof. In some examples, the communication and processing circuitry1642 may send information via one or more channels. In some examples,the communication and processing circuitry 1642 may includefunctionality for a means for sending (e.g., a means for transmitting).In some examples, the communication and processing circuitry 1642 mayinclude functionality for a means for generating, including a means formodulating, a means for encoding, etc.

In some examples, the communication and processing circuitry 1642 may beconfigured to transmit an initial (first) sidelink transmissionincluding a packet over a sidelink data channel to at least onereceiving wireless communication device (e.g., a receiving UE) and anetwork coding device (e.g., which may be one of the receiving UEs) viathe transceiver 1610. In some examples, the communication and processingcircuitry 1642 may further be configured to transmit a network codingrequest flag associated with the packet in the initial sidelinktransmission. For example, the network coding flag may be transmittedwithin SCI-1 of a PSCCH of the initial sidelink transmission, whereasthe packet may be transmitted within a PSSCH of the initial sidelinktransmission.

The communication and processing circuitry 1642 may further beconfigured to receive feedback information 1616 from the one or morereceiving UEs (Rx UEs) and to store the feedback information 1616, forexample within the memory 1605. The communication and processingcircuitry 1642 may further be configured to receive the accept requestmessage 1618 from the network coding device indicating whether thenetwork coding device accepts performing retransmission(s) of the packetand to store the accept request message 1618, for example, within thememory 1605.

The communication and processing circuitry 1642 may further beconfigured to receive the number of slots 1620 and/or the timer duration1622 from the network coding device and to store the number of slots1620 and/or the timer duration 1622 within, for example, the memory1605. In other examples, the number of slots 1620 and/or timer duration1622 may be pre-configured on the wireless communication device orreceived from a base station.

The communication and processing circuitry 1642 may further beconfigured to receive a network coded sidelink transmission including anetwork coded packet from the network coding device. In some examples,the network coded sidelink transmission includes the accept requestmessage. In this example, the network coded packet may include aretransmission of at least one additional packet. In some examples, thenetwork coded packet further includes a retransmission of the packetassociated with the accept request message. The accept request messagemay be included, for example, within SCI-2, a MAC-CE, or a MAC header ofthe network coded sidelink transmission. The communication andprocessing circuitry 1642 may further be configured to receive an acceptrequest indicator from the network coding device that indicates that thenetwork coded sidelink transmission includes the accept request message.For example, the accept request indicator may be included within SCI-1of the network coded sidelink transmission or may be included in adifferent sidelink transmission (e.g., within SCI-1 or SCI-2 of thedifferent sidelink transmission). The communication and processingcircuitry 1642 may further be configured to execute communication andprocessing instructions (software) 1652 stored in the computer-readablemedium 1606 to implement one or more of the functions described herein.

The processor 1604 may further include network coding circuitry 1644,configured to generate the network coding flag requesting the networkcoding device perform retransmission(s) of a packet and to monitor forthe accept request message 1618 from the network coding device. Thenetwork coding circuitry 1644 may monitor for the accept request message1618 at a second time different than a first time at which thecommunication and processing circuitry 1642 receives the feedbackinformation 1616. In some examples, the network coding circuitry 1644may utilize the number of slots 1620 to identify the second time atwhich the accept request message 1618 may be received. For example, theaccept request message 1618 may be delayed with respect to the feedbackinformation 1616 by the number of slots 1620 corresponding to adifference between the first time at which the feedback information 1616is received and the second time at which the accept request message 1618is received.

In some examples, the network coding circuitry 1644 may utilize thetimer duration 1622 to identify the second time at which the acceptrequest message 1618 may be received. For example, the accept requestmessage 1618 may be sent in advance of or delayed with respect to thefeedback information 1616 based on the timer duration 1622. The timerduration 1622 may correspond to a difference between a third time atwhich the communication and processing circuitry 1642 transmits theinitial sidelink transmission including the packet and the second timeat which the accept request message 1618 is received. In some examples,the accept request message 1618 is included in a combined accept requestmessage that includes a combination of a plurality of accept requestmessages for a plurality of packets received by the network codingdevice during the timer duration 1622. In this example, the networkcoding circuitry 1644 may extract the accept request message 1618associated with the packet from the combined accept request message.

In some examples, the network coding circuitry 1644 may be configured toextract the accept request message 1618 from a network coded sidelinktransmission sent by the network coding device. The accept requestmessage 1618 may include an identifier of the wireless communicationdevice 1600, a packet identifier of the packet, and a network codingindicator indicating whether the network coding device acceptsperforming retransmission(s) of the packet. The network coding circuitry1644 may further be configured to determine that the network codedsidelink transmission includes the accept request message 1618 based onthe accept request indicator included in the network coded sidelinktransmission (e.g., SCI-1 of the network coded sidelink transmission) orthe different sidelink transmission. The network coding circuitry 1644may further be configured to execute network coding instructions(software) 1654 stored in the computer-readable medium 1606 to implementone or more of the functions described herein.

FIG. 17 is a flow chart of an exemplary method 1700 for receivingdelayed accept request messages in network coding according to someaspects. As described below, some or all illustrated features may beomitted in a particular implementation within the scope of the presentdisclosure, and some illustrated features may not be required forimplementation of all examples. In some examples, the method may beperformed by the wireless communication device 1600, as described aboveand illustrated in FIG. 16 , by a processor or processing system, or byany suitable means for carrying out the described functions.

At block 1702, the wireless communication device (e.g., a transmittingwireless communication device configured for sidelink communication) maytransmit a sidelink transmission including a first packet and a networkcoding request flag to a receiving wireless communication device and anetwork coding device. The network coding request flag requests thenetwork coding device perform one or more retransmissions of the firstpacket. For example, the communication and processing circuitry 1642,together with the network coding circuitry 1644 and transceiver 1610,shown and described above in connection with FIG. 16 , may provide ameans to transmit the sidelink transmission including the first packetand the network coding request flag.

At block 1704, the transmitting wireless communication device mayreceive feedback information for the first packet from the receivingwireless communication device at a first time. For example, thecommunication and processing circuitry 1642 and transceiver 1610, shownand described above in connection with FIG. 16 , may provide a means toreceive the feedback information at the first time.

At block 1706, the transmitting wireless communication device mayreceive an accept request message from the network coding device at asecond time different than the first time. The accept request messageindicates whether the network coding device accepts performing the oneor more retransmissions of the first packet. In some examples, theaccept request message is delayed with respect to the feedbackinformation by a number of slots corresponding to a difference betweenthe first time and the second time. In some examples, the transmittingwireless communication device may further receive the number of slotsfrom the network coding device.

In some examples, the accept request message is transmitted based on atimer duration corresponding to a difference between a third time atwhich the sidelink transmission is transmitted and the second time. Insome examples, the transmitting wireless communication device mayreceive the timer duration from the network coding device. In someexamples, the transmitting wireless communication device may receive acombined accept request message at the second time that combines aplurality of accept request messages for a plurality of packetstransmitted to the network coding device within the timer duration.

In some examples, the transmitting wireless communication device mayreceive a network coded sidelink transmission including the acceptrequest message and a network coded packet that includes an additionalretransmission of at least one additional packet. In some examples, thenetwork coded packet further includes the retransmission of the firstpacket. In some examples, the accept request message is included withinsecond stage sidelink control information (SCI-2), a medium accesscontrol (MAC) control element (MAC-CE), or a MAC header of the networkcoded sidelink transmission. In some examples, the transmitting wirelesscommunication device may further receive an accept request indicatorfrom the network coding device indicating that the network codedsidelink transmission includes the accept request message. In someexamples, the accept request indicator is included within first stagesidelink control information (SCI-1) of the network coded sidelinktransmission.

In some examples, the accept request message includes an identifier ofthe transmitting wireless communication device, a packet identifier ofthe first packet, and a network coding indicator indicating whether thenetwork coding device accepts the retransmission of the first packet.For example, the communication and processing circuitry 1642, togetherwith the network coding circuitry 1644 and transceiver 1610, shown anddescribed above in connection with FIG. 16 , may provide a means toreceive the accept request message at the second time different than thefirst time.

In one configuration, the wireless communication device 1600 includesmeans for transmitting a sidelink transmission to a receiving wirelesscommunication device and a network coding device, where the sidelinktransmission includes a first packet and a network coding request flagrequesting retransmission of the first packet by the network codingdevice. The wireless communication device 1600 further includes meansfor receiving feedback information for the first packet from thereceiving wireless communication device at a first time and means forreceiving an accept request message from the network coding device at asecond time different than the first time, where the accept requestmessage indicating whether the network coding device accepts theretransmission of the first packet. In one aspect, the aforementionedmeans may be the processor 1604 shown in FIG. 16 configured to performthe functions recited by the aforementioned means. In another aspect,the aforementioned means may be a circuit or any apparatus configured toperform the functions recited by the aforementioned means.

Of course, in the above examples, the circuitry included in theprocessor 1604 is merely provided as an example, and other means forcarrying out the described functions may be included within variousaspects of the present disclosure, including but not limited to theinstructions stored in the computer-readable storage medium 1606, or anyother suitable apparatus or means described in any one of the FIGS. 1,3, 6, 7, 9, 10 , and/or 14, and utilizing, for example, the processesand/or algorithms described herein in relation to FIGS. 10-14 , and/or17.

FIG. 18 is a conceptual diagram illustrating an example of a hardwareimplementation for an exemplary network coding device 1800 employing aprocessing system 1814. For example, the network coding device 1800 maycorrespond to a wireless communication device (e.g., a sidelink device,such as a V2X device, D2D device, RSU, or other UE or wirelesscommunication device configured for sidelink communication) or a basestation (e.g., gNB) illustrated in any one or more of FIGS. 1, 3, 6, 7,9, 10 , and/or 14.

In accordance with various aspects of the disclosure, an element, or anyportion of an element, or any combination of elements may be implementedwith a processing system 1814 that includes one or more processors 1804.The processing system 1814 may be substantially the same as theprocessing system 1614 illustrated in FIG. 16 , including a businterface 1808, a bus 1802, memory 1805, a processor 1804, and acomputer-readable medium 1806. For example, the memory 1805 may storeone or more packets (Packet(s)) 1815, one or more network coding flags(NC Flag(s)) 1816, feedback information (Feedback) 1818, a number ofslots (#of Slots) 1820, and a timer duration (Timer Duration) 1822,which may be used by the processor 1804 in generating and/or processingsidelink transmissions. Furthermore, the network coding device 1800 mayinclude an optional user interface 1812, a transceiver 1810, andantenna(s) 1830 substantially similar to those described above in FIG.16 . The processor 1804, as utilized in a network coding device 1800,may be used to implement any one or more of the processes describedbelow. In some examples, the computer-readable medium 1806 may beimplemented on an article of manufacture, which may further include oneor more other elements or circuits, such as the processor 1804 and/ormemory 1805.

In some aspects of the disclosure, the processor 1804 may includecircuitry configured for various functions. For example, the processor1804 may include communication and processing circuitry 1842, configuredto communicate with one or more wireless communication devices (e.g.,UEs) via respective sidelinks (e.g., PC5 interfaces) and/or access(e.g., Uu) links The communication and processing circuitry 1842 mayfurther be configured to communicate with a base station via one or moreaccess (e.g., Uu) links In some examples, the communication andprocessing circuitry 1842 may include one or more hardware componentsthat provide the physical structure that performs processes related towireless communication (e.g., signal reception and/or signaltransmission) and signal processing (e.g., processing a received signaland/or processing a signal for transmission). For example, thecommunication and processing circuitry 1842 may include one or moretransmit/receive chains.

In some implementations where the communication involves receivinginformation, the communication and processing circuitry 1842 may obtaininformation from a component of the network coding device 1800 (e.g.,from the transceiver 1810 that receives the information via radiofrequency signaling or some other type of signaling suitable for theapplicable communication medium), process (e.g., decode) theinformation, and output the processed information. For example, thecommunication and processing circuitry 1842 may output the informationto another component of the processor 1804, to the memory 1805, or tothe bus interface 1808. In some examples, the communication andprocessing circuitry 1842 may receive one or more of signals, messages,other information, or any combination thereof. In some examples, thecommunication and processing circuitry 1842 may receive information viaone or more channels. In some examples, the communication and processingcircuitry 1842 may include functionality for a means for receiving. Insome examples, the communication and processing circuitry 1842 mayinclude functionality for a means for processing, including a means fordemodulating, a means for decoding, etc.

In some implementations where the communication involves sending (e.g.,transmitting) information, the communication and processing circuitry1842 may obtain information (e.g., from another component of theprocessor 1804, the memory 1805, or the bus interface 1808), process(e.g., modulate, encode, etc.) the information, and output the processedinformation. For example, the communication and processing circuitry1842 may output the information to the transceiver 1810 (e.g., thattransmits the information via radio frequency signaling or some othertype of signaling suitable for the applicable communication medium). Insome examples, the communication and processing circuitry 1842 may sendone or more of signals, messages, other information, or any combinationthereof. In some examples, the communication and processing circuitry1842 may send information via one or more channels. In some examples,the communication and processing circuitry 1842 may includefunctionality for a means for sending (e.g., a means for transmitting).In some examples, the communication and processing circuitry 1842 mayinclude functionality for a means for generating, including a means formodulating, a means for encoding, etc.

In some examples, the communication and processing circuitry 1842 may beconfigured to receive a first sidelink transmission transmitted from afirst transmitting wireless communication device to one or morereceiving wireless communication devices via the transceiver 1810. Thefirst sidelink transmission may include a first packet 1815 transmittedover a sidelink data channel (e.g., a PSSCH). The first sidelinktransmission may further include a first network coding request flag1816 requesting the network coding device 1800 perform one or moreretransmissions of the first packet 1815. The communication andprocessing circuitry 1842 may be configured to store the first packet1815 and the first network coding request flag 1816 within, for example,memory 1805.

The communication and processing circuitry 1842 may further beconfigured to receive feedback information 1818 for the first packetfrom the one or more receiving wireless communication devices via thetransceiver 1810. In some examples, the communication and processingcircuitry 1842 may receive the feedback information 1818 at a firsttime.

The communication and processing circuitry 1842 may further beconfigured to transmit a first accept request message to the firsttransmitting wireless communication device indicating whether thenetwork coding device 1800 accepts performing retransmission(s) of thefirst packet 1815 via the transceiver 1810. The communication andprocessing circuitry 1842 may be configured to transmit the first acceptrequest message at a second time different than the first time. In someexamples, a difference between the first time and the second time maycorrespond to the number of slots 1820. In this example, thecommunication and processing circuitry 1842 may further be configured totransmit the number of slots 1820 to the first transmitting wirelesscommunication device.

In some examples, the communication and processing circuitry 1842 maytransmit the first accept request message at the second time uponexpiration of a timer initiated with the timer duration 1822 uponreceipt of the first sidelink transmission. In this example, thecommunication and processing circuitry 1842 may further be configured totransmit the timer duration 1822 of the timer to the first transmittingwireless communication device. In some examples, the communication andprocessing circuitry 1842 may receive a plurality of sidelinktransmissions including the first sidelink transmission prior toexpiration of the timer. Each of the plurality of sidelink transmissionscan include a respective one of a plurality of packets 1815 and arespective one of a plurality of network coding request flags 1816, eachof which may be stored, for example, in memory 1805. In this example,the communication and processing circuitry 1842 may be configured totransmit a combined accept request message combining a plurality ofaccept request messages including the first accept request message to atleast the first transmitting wireless communication device uponexpiration of the timer. In examples in which the plurality of packetsare received from multiple, different transmitting wirelesscommunication devices, the communication and processing circuitry 1842may groupcast or multicast the combined accept request message to themultiple transmitting wireless communication devices.

The communication and processing circuitry 1842 may further beconfigured to retransmit the packet to the one or more receivingwireless communication devices as a network coded sidelink transmissionbased on the network coding request flag via the transceiver 1810. Insome examples, the communication and processing circuitry 1842 may beconfigured to retransmit the packet and one or more additional packetsas the network coded sidelink transmission.

In some examples, the communication and processing circuitry 1842 may beconfigured to transmit a network coded sidelink transmission includingthe first accept request message and a network coded packet including atleast an additional retransmission of an additional packet via thetransceiver 1810. In some examples, the network coded packet furtherincludes the retransmission of the first packet. In some examples, thefirst accept request message is included within second stage sidelinkcontrol information (SCI-2), a medium access control (MAC) controlelement (MAC-CE), or a MAC header of the network coded sidelinktransmission. In some examples, the communication and processingcircuitry 1842 may further be configured to transmit an accept requestindicator to the first transmitting wireless communication deviceindicating that the network coded sidelink transmission includes thefirst accept request message via the transceiver 1810. In some examples,the accept request indicator is included within first stage sidelinkcontrol information (SCI-1) of the network coded sidelink transmissionor within a different sidelink transmission (e.g., within SCI-1 or SCI-2of the different sidelink transmission). The communication andprocessing circuitry 1842 may further be configured to executecommunication and processing instructions (software) 1852 stored in thecomputer-readable medium 1806 to implement one or more of the functionsdescribed herein.

The processor 1804 may further include network coding circuitry 1844,configured to generate the first accept request message for the firsttransmitting wireless communication device and to delay transmission ofthe first accept request message from the first time at which thefeedback information 1818 for the first packet 1815 is received to thesecond time. In some examples, the network coding circuitry 1844 may beconfigured to delay transmission of the first accept request message bythe number of slots 1820. In some examples, the network coding circuitry1844 may be configured to determine the number of slots based on atleast one of a priority of the first packet or a packet delay budgetassociated with the first packet.

In some examples, the network coding circuitry 1844 may be configured todelay transmission of the first accept request message based on thetimer duration 1822 of the timer. For example, the network codingcircuitry 1844 may be configured to set the timer upon receipt of thefirst sidelink transmission and to instruct the communication andprocessing circuitry 1842 to transmit the first accept request messageupon expiration of the timer. In some examples, the network codingcircuitry 1844 may be configured to determine the timer duration 1822based on at least one of a priority of the first packet or a packetdelay budget associated with the first packet.

In some examples, the network coding circuitry 1844 may be configured togenerate the plurality of accept request messages including the firstaccept request message for the plurality of packets including the firstpacket received during the timer duration 1822. The network codingcircuitry 1844 may further be configured to combine the plurality ofaccept request messages to produce the combined accept request message.

In some examples, the network coding circuitry 1844 may be configured togenerate the network coded sidelink transmission including the firstaccept request message and the network coded packet including at leastthe additional retransmission of the additional packet. In someexamples, the network coding circuitry 1844 may generate the networkcoded packet further including the retransmission of the first packet.For example, the network coding circuitry 1844 may include theretransmission of the first packet 1815 in the network coded packet inresponse to accepting retransmission(s) of the first packet 1815. Insome examples, the network coding circuitry 1844 may utilize thefeedback information 1818 in generating the network coded packet.

In some examples, the first accept request message may include anidentifier of the first transmitting wireless communication device, apacket identifier of the first packet 1815, and a network codingindicator indicating whether the network coding device 1800 accepts theretransmission of the first packet. The network coding circuitry 1844may further be configured to generate the accept request indicator andto include the accept request indicator within SCI-1 of the networkcoded sidelink transmission or within a different sidelink transmission.The network coding circuitry 1844 may further be configured to executenetwork coding instructions (software) 1854 stored in thecomputer-readable medium 1806 to implement one or more of the functionsdescribed herein.

FIG. 19 is a flow chart of an exemplary method 1900 for network codingaccording to some aspects. As described below, some or all illustratedfeatures may be omitted in a particular implementation within the scopeof the present disclosure, and some illustrated features may not berequired for implementation of all examples. In some examples, themethod may be performed by the network coding device 1800, as describedabove and illustrated in FIG. 18 , by a processor or processing system,or by any suitable means for carrying out the described functions.

At block 1902, the network coding device (e.g., a roadside unit (RSU),another wireless communication device, or a base station) may receive afirst sidelink transmission transmitted from a transmitting wirelesscommunication device to a receiving wireless communication device. Thefirst sidelink transmission includes a first packet and a first networkcoding request flag requesting the network coding device perform one ormore retransmissions of the first packet. For example, the communicationand processing circuitry 1842 and transceiver 1810 shown and describedabove in connection with FIG. 18 may provide a means to receive thefirst sidelink transmission.

At block 1904, the network coding device may receive feedbackinformation for the first packet from the receiving wirelesscommunication device at a first time. For example, the communication andprocessing circuitry 1842 and transceiver 1810, shown and describedabove in connection with FIG. 18 , may provide a means to receive thefeedback information.

At block 1906, the network coding device may transmit a first acceptrequest message to the transmitting wireless communication device at asecond time different than the first time indicating whether the networkcoding device accepts performing the one or more retransmissions of thefirst packet. In some examples, the network coding device may delaytransmission of the first accept request message by a number of slotscorresponding to a difference between the first time and the secondtime. In some examples, the number of slots is based on at least one ofa priority of the first packet or a packet delay budget associated withthe first packet. In some examples, the network coding device mayfurther transmit the number of slots to the transmitting wirelesscommunication device.

In some examples, the network coding device may set a timer upon receiptof the first sidelink transmission and transmit the first accept requestmessage upon expiration of the timer. In some examples, a timer durationof the timer is based on at least one of a priority of the first packetor a packet delay budget associated with the first packet. In someexamples, the network coding device may further transmit the timerduration of the timer to the transmitting wireless communication device.In some examples, the network coding device may receive a plurality ofsidelink transmissions including the first sidelink transmission priorto expiration of the timer. Each of the plurality of sidelinktransmissions includes a respective one of a plurality of packets and arespective one of a plurality of network coding request flags. In someexamples, the network coding device may further combine a plurality ofaccept request messages including the first accept request message toproduce a combined accept request message for the plurality of packets.The network coding device may further transmit the combined acceptrequest message to at least the transmitting wireless communicationdevice upon expiration of the timer.

In some examples, the network coding device may transmit a network codedsidelink transmission including the first accept request message and anetwork coded packet including at least an additional retransmission ofan additional packet. In some examples, the network coded packet furtherincludes the retransmission of the first packet. In some examples, thenetwork coding device may include the first accept request messagewithin second stage sidelink control information (SCI-2), a mediumaccess control (MAC) control element (MAC-CE), or a MAC header of thenetwork coded sidelink transmission. In some examples, the networkcoding device may transmit an accept request indicator to thetransmitting wireless communication device. The accept request indicatorindicates that the network coded sidelink transmission comprises thefirst accept request message. In some examples, the accept requestmessage is included within first stage sidelink control information(SCI-1) of the network coded sidelink transmission. For example, thecommunication and processing circuitry 1842, together with the networkcoding circuitry 1844 and transceiver 1810 shown and described above inconnection with FIG. 18 may provide a means to transmit the first acceptrequest message.

In one configuration, the network coding device 1800 includes means forreceiving a first sidelink transmission transmitted from a transmittingwireless communication device to a receiving wireless communicationdevice, where the first sidelink transmission includes a first packetand a first network coding request flag requesting retransmission of thefirst packet by the network coding device, as described in the presentdisclosure. The network coding device 1800 further includes means forreceiving feedback information for the first packet from the receivingwireless communication device at a first time and means for transmittinga first accept request message to the transmitting wirelesscommunication device at a second time different than the first time,where the first accept request message indicates whether the networkcoding device accepts the retransmission of the first packet. In oneaspect, the aforementioned means may be the processor 1804 shown in FIG.18 configured to perform the functions recited by the aforementionedmeans. In another aspect, the aforementioned means may be a circuit orany apparatus configured to perform the functions recited by theaforementioned means.

Of course, in the above examples, the circuitry included in theprocessor 1804 is merely provided as an example, and other means forcarrying out the described functions may be included within variousaspects of the present disclosure, including but not limited to theinstructions stored in the computer-readable storage medium 1806, or anyother suitable apparatus or means described in any one of the FIGS. 1,3, 6, 8, 9, 10 and/or 14 , and utilizing, for example, the processesand/or algorithms described herein in relation to FIGS. 10-14, and 19 .

The processes shown in FIGS. 10-14, 17, and 19 may include additionalaspects, such as any single aspect or any combination of aspectsdescribed below and/or in connection with one or more other processesdescribed elsewhere herein.

Aspect 1: A method for wireless communication at a network codingdevice, the method comprising: receiving a first sidelink transmissiontransmitted from a transmitting wireless communication device to areceiving wireless communication device, the first sidelink transmissioncomprising a first packet and a first network coding request flagrequesting retransmission of the first packet by the network codingdevice; receiving feedback information for the first packet from thereceiving wireless communication device at a first time; andtransmitting a first accept request message to the transmitting wirelesscommunication device at a second time different than the first time, thefirst accept request message indicating whether the network codingdevice accepts the retransmission of the first packet.

Aspect 2: The method of aspect 1, further comprising: delayingtransmission of the first accept request message by a number of slotscorresponding to a difference between the first time and the secondtime.

Aspect 3: The method of aspect 2, wherein the number of slots is basedon at least one of a priority of the first packet or a packet delaybudget associated with the first packet.

Aspect 4: The method of aspect 2 or 3, further comprising: transmittingthe number of slots to the transmitting wireless communication device.

Aspect 5: The method of aspect 1, further comprising: setting a timerupon receipt of the first sidelink transmission, and wherein thetransmitting the first accept request message further comprises:transmitting the first accept request message upon expiration of thetimer.

Aspect 6: The method of aspect 5, further comprising: receiving aplurality of sidelink transmissions including the first sidelinktransmission prior to expiration of the timer, each of the plurality ofsidelink transmissions comprising a respective one of a plurality ofpackets and a respective one of a plurality of network coding requestflags; combining a plurality of accept request messages including thefirst accept request message to produce a combined accept requestmessage for the plurality of packets; and transmitting the combinedaccept request message to at least the transmitting wirelesscommunication device upon expiration of the timer.

Aspect 7: The method of aspect 5 or 6, wherein a timer duration of thetimer is based on at least one of a priority of the first packet or apacket delay budget associated with the first packet.

Aspect 8: The method of any of aspects 5 through 7, further comprising:transmitting a timer duration of the timer to the transmitting wirelesscommunication device.

Aspect 9: The method of aspect 1, wherein the transmitting the acceptrequest message further comprises: transmitting a network coded sidelinktransmission comprising the first accept request message and a networkcoded packet comprising at least an additional retransmission of anadditional packet.

Aspect 10: The method of aspect 9, further comprising: including thefirst accept request message within second stage sidelink controlinformation (SCI-2), a medium access control (MAC) control element(MAC-CE), or a MAC header of the network coded sidelink transmission.

Aspect 11: The method of aspect 9 or 10, wherein the first acceptrequest message comprises an identifier of the transmitting wirelesscommunication device, a packet identifier of the first packet, and anetwork coding indicator indicating whether the network coding deviceaccepts the retransmission of the first packet.

Aspect 12: The method of any of aspects 9 through 11, furthercomprising: transmitting an accept request indicator to the transmittingwireless communication device, the accept request indicator indicatingthat the network coded sidelink transmission comprises the first acceptrequest message.

Aspect 13: The method of aspect 12, wherein the accept request indicatoris included within first stage sidelink control information (SCI-1) ofthe network coded sidelink transmission.

Aspect 14: The method of any of aspects 9 through 13, wherein thenetwork coded packet further comprises the retransmission of the firstpacket.

Aspect 15: A network coding device comprising a transceiver, a memory,and a processor coupled to the transceiver and the memory, the processorand the memory configured to perform a method of any one of aspects 1through 14.

Aspect 16: A network coding device comprising means for performing amethod of any one of aspects 1 through 14.

Aspect 17: A non-transitory computer-readable medium having storedtherein instructions executable by one or more processors of a networkcoding device to perform a method of any one of examples 1 through 14.

Aspect 18: A method for wireless communication at a transmittingwireless communication device, the method comprising: transmitting asidelink transmission to a receiving wireless communication device and anetwork coding device, the sidelink transmission comprising a firstpacket and a network coding request flag requesting retransmission ofthe first packet by the network coding device; receiving feedbackinformation for the first packet from the receiving wirelesscommunication device at a first time; and receiving an accept requestmessage from the network coding device at a second time different thanto the first time, the accept request message indicating whether thenetwork coding device accepts the retransmission of the first packet.

Aspect 19: The method of aspect 18, wherein the accept request messageis delayed with respect to the feedback information by a number of slotscorresponding to a difference between the first time and the secondtime.

Aspect 20: The method of aspect 18 or 19, further comprising: receivingthe number of slots from the network coding device.

Aspect 21: The method of aspect 18, wherein the accept request messageis received based on a timer duration corresponding to a differencebetween a third time at which the sidelink transmission is transmittedand the second time.

Aspect 22: The method of aspect 21, wherein the receiving the acceptrequest message further comprises: receiving a combined accept requestmessage at the second time that combines a plurality of accept requestmessages for a plurality of packets transmitted to the network codingdevice within the timer duration.

Aspect 23: The method of aspect 21 or 22, further comprising: receivingthe timer duration from the network coding device.

Aspect 24: The method of aspect 18, wherein the receiving the acceptrequest message further comprises: receiving a network coded sidelinktransmission comprising the accept request message and a network codedpacket comprising an additional retransmission of at least oneadditional packet.

Aspect 25: The method of aspect 24, wherein the accept request messageis included within second stage sidelink control information (SCI-2), amedium access control (MAC) control element (MAC-CE), or a MAC header ofthe network coded sidelink transmission.

Aspect 26: The method of aspect 24 or 25, wherein the accept requestmessage comprises an identifier of the transmitting wirelesscommunication device, a packet identifier of the first packet, and anetwork coding indicator indicating whether the network coding deviceaccepts the retransmission of the first packet.

Aspect 27: The method of any of aspects 24 through 26, furthercomprising: receiving an accept request indicator from the networkcoding device, the accept request indicator indicating that the networkcoded sidelink transmission comprises the accept request message.

Aspect 28: The method of aspect 27, wherein the accept request indicatoris included within first stage sidelink control information (SCI-1) ofthe network coded sidelink transmission.

Aspect 29: The method of any of aspects 24 through 28, wherein thenetwork coded packet further comprises the retransmission of the firstpacket.

Aspect 30: A transmitting wireless communication device comprising atransceiver, a memory, and a processor coupled to the transceiver andthe memory, the processor and the memory configured to perform a methodof any one of aspects 18 through 29.

Aspect 31: A transmitting wireless communication device comprising meansfor performing a method of any one of aspects 18 through 29.

Aspect 32: A non-transitory computer-readable medium having storedtherein instructions executable by one or more processors of atransmitting wireless communication device to perform a method of anyone of examples 18 through 29.

Several aspects of a wireless communication network have been presentedwith reference to an exemplary implementation. As those skilled in theart will readily appreciate, various aspects described throughout thisdisclosure may be extended to other telecommunication systems, networkarchitectures and communication standards.

By way of example, various aspects may be implemented within othersystems defined by 3GPP, such as Long-Term Evolution (LTE), the EvolvedPacket System (EPS), the Universal Mobile Telecommunication System(UMTS), and/or the Global System for Mobile (GSM). Various aspects mayalso be extended to systems defined by the 3rd Generation PartnershipProject 2 (3GPP2), such as CDMA2000 and/or Evolution-Data Optimized(EV-DO). Other examples may be implemented within systems employing IEEE802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Ultra-Wideband (UWB),Bluetooth, and/or other suitable systems. The actual telecommunicationstandard, network architecture, and/or communication standard employedwill depend on the specific application and the overall designconstraints imposed on the system.

Within the present disclosure, the word “exemplary” is used to mean“serving as an example, instance, or illustration.” Any implementationor aspect described herein as “exemplary” is not necessarily to beconstrued as preferred or advantageous over other aspects of thedisclosure. Likewise, the term “aspects” does not require that allaspects of the disclosure include the discussed feature, advantage ormode of operation. The term “coupled” is used herein to refer to thedirect or indirect coupling between two objects. For example, if objectA physically touches object B, and object B touches object C, thenobjects A and C may still be considered coupled to one another—even ifthey do not directly physically touch each other. For instance, a firstobject may be coupled to a second object even though the first object isnever directly physically in contact with the second object. The terms“circuit” and “circuitry” are used broadly, and intended to include bothhardware implementations of electrical devices and conductors that, whenconnected and configured, enable the performance of the functionsdescribed in the present disclosure, without limitation as to the typeof electronic circuits, as well as software implementations ofinformation and instructions that, when executed by a processor, enablethe performance of the functions described in the present disclosure.

One or more of the components, steps, features and/or functionsillustrated in FIGS. 1-19 may be rearranged and/or combined into asingle component, step, feature or function or embodied in severalcomponents, steps, or functions. Additional elements, components, steps,and/or functions may also be added without departing from novel featuresdisclosed herein. The apparatus, devices, and/or components illustratedin FIGS. 1, 3, 6, 7, 9-14, 16 , and/or 18 may be configured to performone or more of the methods, features, or steps described herein. Thenovel algorithms described herein may also be efficiently implemented insoftware and/or embedded in hardware.

It is to be understood that the specific order or hierarchy of steps inthe methods disclosed is an illustration of exemplary processes. Basedupon design preferences, it is understood that the specific order orhierarchy of steps in the methods may be rearranged. The accompanyingmethod claims present elements of the various steps in a sample orderand are not meant to be limited to the specific order or hierarchypresented unless specifically recited therein.

The previous description is provided to enable any person skilled in theart to practice the various aspects described herein. Variousmodifications to these aspects will be readily apparent to those skilledin the art, and the generic principles defined herein may be applied toother aspects. Thus, the claims are not intended to be limited to theaspects shown herein, but are to be accorded the full scope consistentwith the language of the claims, wherein reference to an element in thesingular is not intended to mean “one and only one” unless specificallyso stated, but rather “one or more.” Unless specifically statedotherwise, the term “some” refers to one or more. A phrase referring to“at least one of” a list of items refers to any combination of thoseitems, including single members. As an example, “at least one of: a, b,or c” is intended to cover: a; b; c; a and b; a and c; b and c; and a,b, and c. All structural and functional equivalents to the elements ofthe various aspects described throughout this disclosure that are knownor later come to be known to those of ordinary skill in the art areexpressly incorporated herein by reference and are intended to beencompassed by the claims. Moreover, nothing disclosed herein isintended to be dedicated to the public regardless of whether suchdisclosure is explicitly recited in the claims.

What is claimed is:
 1. A network coding device, comprising: atransceiver; a memory; and a processor coupled to the transceiver andthe memory, wherein the processor and the memory are configured to:receive a first sidelink transmission transmitted from a transmittingwireless communication device to a receiving wireless communicationdevice via the transceiver, the first sidelink transmission comprising afirst packet and a first network coding request flag requesting thenetwork coding device perform one or more retransmissions of the firstpacket; receive feedback information for the first packet from thereceiving wireless communication device at a first time via thetransceiver; transmit a first accept request message to the transmittingwireless communication device at a second time different than the firsttime via the transceiver, the first accept request message indicatingwhether the network coding device accepts performing the one or moreretransmissions of the first packet; and delay transmission of the firstaccept request message by a number of slots corresponding to adifference between the first time and the second time.
 2. The networkcoding device of claim 1, wherein the number of slots is based on atleast one of a priority of the first packet or a packet delay budgetassociated with the first packet.
 3. The network coding device of claim1, wherein the processor and the memory are further configured to:transmit the number of slots to the transmitting wireless communicationdevice.
 4. A network coding device, comprising: a transceiver; a memory;and a processor coupled to the transceiver and the memory, wherein theprocessor and the memory are configured to: receive a first sidelinktransmission transmitted from a transmitting wireless communicationdevice to a receiving wireless communication device via the transceiver,the first sidelink transmission comprising a first packet and a firstnetwork coding request flag requesting the network coding device performone or more retransmissions of the first packet; receive feedbackinformation for the first packet from the receiving wirelesscommunication device at a first time via the transceiver; transmit afirst accept request message to the transmitting wireless communicationdevice at a second time different than the first time via thetransceiver, the first accept request message indicating whether thenetwork coding device accepts performing the one or more retransmissionsof the first packet; and set a timer upon receipt of the first sidelinktransmission; and transmit the first accept request message uponexpiration of the timer.
 5. The network coding device of claim 4,wherein the processor and the memory are further configured to: receivea plurality of sidelink transmissions including the first sidelinktransmission prior to expiration of the timer, each of the plurality ofsidelink transmissions comprising a respective one of a plurality ofpackets and a respective one of a plurality of network coding requestflags; combine a plurality of accept request messages including thefirst accept request message to produce a combined accept requestmessage for the plurality of packets; and transmit the combined acceptrequest message to at least the transmitting wireless communicationdevice upon expiration of the timer.
 6. The network coding device ofclaim 4, wherein a timer duration of the timer is based on at least oneof a priority of the first packet or a packet delay budget associatedwith the first packet.
 7. The network coding device of claim 4, whereinthe processor and the memory are further configured to: transmit a timerduration of the timer to the transmitting wireless communication device.8. A network coding device, comprising: a transceiver; a memory; and aprocessor coupled to the transceiver and the memory, wherein theprocessor and the memory are configured to: receive a first sidelinktransmission transmitted from a transmitting wireless communicationdevice to a receiving wireless communication device via the transceiver,the first sidelink transmission comprising a first packet and a firstnetwork coding request flag requesting the network coding device performone or more retransmissions of the first packet; receive feedbackinformation for the first packet from the receiving wirelesscommunication device at a first time via the transceiver; transmit afirst accept request message to the transmitting wireless communicationdevice at a second time different than the first time via thetransceiver, the first accept request message indicating whether thenetwork coding device accepts performing the one or more retransmissionsof the first packet; and transmit a network coded sidelink transmissioncomprising the first accept request message and a network coded packetcomprising at least an additional retransmission of an additionalpacket.
 9. The network coding device of claim 8, wherein the processorand the memory are further configured to: include the first acceptrequest message within second stage sidelink control information(SCI-2), a medium access control (MAC) control element (MAC-CE), or aMAC header of the network coded sidelink transmission.
 10. The networkcoding device of claim 8, wherein the first accept request messagecomprises an identifier of the transmitting wireless communicationdevice, a packet identifier of the first packet, and a network codingindicator indicating whether the network coding device acceptsperforming the one or more retransmissions of the first packet.
 11. Thenetwork coding device of claim 8, wherein the processor and the memoryare further configured to: transmit an accept request indicator to thetransmitting wireless communication device, the accept request indicatorindicating that the network coded sidelink transmission comprises thefirst accept request message.
 12. The network coding device of claim 11,wherein the accept request indicator is included within first stagesidelink control information (SCI-1) of the network coded sidelinktransmission.
 13. The network coding device of claim 8, wherein thenetwork coded packet further comprises a retransmission of the one ormore retransmissions of the first packet.
 14. A method for wirelesscommunication at a network coding device, the method comprising:receiving a first sidelink transmission transmitted from a transmittingwireless communication device to a receiving wireless communicationdevice, the first sidelink transmission comprising a first packet and afirst network coding request flag requesting the network coding deviceperform one or more retransmissions of the first packet; receivingfeedback information for the first packet from the receiving wirelesscommunication device at a first time; transmitting a first acceptrequest message to the transmitting wireless communication device at asecond time different than the first time, the first accept requestmessage indicating whether the network coding device accepts performingthe one or more retransmissions of the first packet; and delayingtransmission of the first accept request message by a number of slotscorresponding to a first difference between the first time and thesecond time or based on a timer duration corresponding to a seconddifference between a third time at which the first sidelink transmissionis received and the second time.
 15. The method of claim 14, wherein thenumber of slots is based on at least one of a priority of the firstpacket or a packet delay budget associated with the first packet. 16.The method of claim 14, further comprising: transmitting the number ofslots to the transmitting wireless communication device.
 17. The methodof claim 14, further comprising: setting a timer having the timerduration upon receipt of the first sidelink transmission; andtransmitting the first accept request message upon expiration of thetimer.
 18. The method of claim 17, further comprising: receiving aplurality of sidelink transmissions including the first sidelinktransmission prior to expiration of the timer, each of the plurality ofsidelink transmissions comprising a respective one of a plurality ofpackets and a respective one of a plurality of network coding requestflags; combining a plurality of accept request messages including thefirst accept request message to produce a combined accept requestmessage for the plurality of packets; and transmitting the combinedaccept request message to at least the transmitting wirelesscommunication device upon expiration of the timer.
 19. The method ofclaim 17, wherein the timer duration of the timer is based on at leastone of a priority of the first packet or a packet delay budgetassociated with the first packet.
 20. The method of claim 17, furthercomprising: transmitting the timer duration of the timer to thetransmitting wireless communication device.
 21. A method for wirelesscommunication at a network coding device, the method comprising:receiving a first sidelink transmission transmitted from a transmittingwireless communication device to a receiving wireless communicationdevice, the first sidelink transmission comprising a first packet and afirst network coding request flag requesting the network coding deviceperform one or more retransmissions of the first packet; receivingfeedback information for the first packet from the receiving wirelesscommunication device at a first time; transmitting a first acceptrequest message to the transmitting wireless communication device at asecond time different than the first time, the first accept requestmessage indicating whether the network coding device accepts performingthe one or more retransmissions of the first packet; and transmitting anetwork coded sidelink transmission comprising the first accept requestmessage and a network coded packet comprising at least an additionalretransmission of an additional packet.
 22. The method of claim 21,further comprising: including the first accept request message withinsecond stage sidelink control information (SCI-2), a medium accesscontrol (MAC) control element (MAC-CE), or a MAC header of the networkcoded sidelink transmission.
 23. The method of claim 21, wherein thefirst accept request message comprises an identifier of the transmittingwireless communication device, a packet identifier of the first packet,and a network coding indicator indicating whether the method acceptsperforming the one or more retransmissions of the first packet.
 24. Themethod of claim 21, further comprising: transmitting an accept requestindicator to the transmitting wireless communication device, the acceptrequest indicator indicating that the network coded sidelinktransmission comprises the first accept request message.
 25. The methodof claim 24, wherein the accept request indicator is included withinfirst stage sidelink control information (SCI-1) of the network codedsidelink transmission.
 26. The method of claim 21, wherein the networkcoded packet further comprises a retransmission of the one or moreretransmissions of the first packet.
 27. A network coding device,comprising: means for receiving a first sidelink transmissiontransmitted from a transmitting wireless communication device to areceiving wireless communication device, the first sidelink transmissioncomprising a first packet and a first network coding request flagrequesting the network coding device perform one or more retransmissionsof the first packet; means for receiving feedback information for thefirst packet from the receiving wireless communication device at a firsttime; means for transmitting a first accept request message to thetransmitting wireless communication device at a second time differentthan the first time, the first accept request message indicating whetherthe network coding device accepts performing the one or moreretransmissions of the first packet; and means for delaying transmissionof the first accept request message by a number of slots correspondingto a first difference between the first time and the second time orbased on a timer duration corresponding to a second difference between athird time at which the first sidelink transmission is received and thesecond time.